doc: De-duplicate readme and license files ...

The readme.rst and license.rst files in the project root overlap
with the index.rst and license.rst files in the docs/ folder. We
need to use the latter when building the documentation, as Sphinx
requires all included files to be under a common root. However,
the files in the root are currently used by the cgit and Github
viewers.

Using symlinks in Git presents some difficulties so the best
course of action is likely to leave these files but in stub form.

The license.rst file in the root will simply tell the reader to
refer to docs/license.rst.

The readme.rst file will contain a small amount of content that
is derived from the docs/index.rst file, so that the Github main
page will have something valid to show, but it will also contain
a link to the full documentation on ReadTheDocs.

Change-Id: I6dc46f08777e8d7ecb32ca7afc07a28486c9f77a
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

doc: Convert internal links to RST format ...

Currently links between documents are using the format:

<path/to/><filename>.rst

This was required for services like GitHub because they render each
document in isolation - linking to another document is like linking
to any other file, just provide the full path.

However, with the new approach, the .rst files are only the raw
source for the documents. Once the documents have been rendered
the output is now in another format (HTML in our case) and so,
when linking to another document, the link must point to the
rendered version and not the .rst file.

The RST spec provides a few methods for linking between content.
The parent of this patch enabled the automatic creation of anchors
for document titles - we will use these anchors as the targets for
our links. Additional anchors can be added by hand if needed, on
section and sub-section titles, for example.

An example of this new format, for a document with the title
"Firmware Design" is :ref:`Firmware Design`.

One big advantage of this is that anchors are not dependent on
paths. We can then move documents around, even between directories,
without breaking any links between documents. Links will need to be
updated only if the title of a document changes.

Change-Id: I9e2340a61dd424cbd8fd1ecc2dc166f460d81703
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

Rename Cortex-Deimos to Cortex-A77 ...

Change-Id: I755e4c42242d9a052570fd1132ca3d937acadb13
Signed-off-by: Balint Dobszay <balint.dobszay@arm.com>

Add information about the mailing list in the docs ...

Change-Id: I41ce5323c33a81db13c5cc40de1ac4e221a10cd8
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>

Removing IRC related info from the documentation ...

Change-Id: I5cf8c70a304bf5869cbeb12fa8d39171cff48ebd
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>

Further fixes to documentation links ...

Change-Id: Ib021c721652d96f6c06ea18741f19a72bba1d00f
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>

doc: Use proper note and warning annotations ...

The documentation contains plenty of notes and warnings. Enable
special rendering of these blocks by converting the note prefix
into a .. note:: annotation.

Change-Id: I34e26ca6bf313d335672ab6c2645741900338822
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

doc: Add minimal glossary ...

One of the current issues with the documentation is that terms and
abbreviations are frequently redefined. For example, we might have
a sentence like "... the SCP (System Control Processor) will ...".

These definitions might be repeated several times across pages, or
even within the same document. Equally, some of these abbreviations
are missed and are never expanded.

Sphinx provides a :term: keyword that takes some text and,
if that text is defined in a glossary document, links to its glossary
entry. Using this functionality will prevent repeated definitions
and will make the docs more maintainable by using a single
definition source.

The glossary added in this patch was created from a quick scrub of
the source code - there may be missing entries. The SDEI abbreviation
was used as an example.

Note that a global_substitutions file was created. This file contains
the RST 'replace' statements that convert plain text terms into linked
terms (by adding the ':term:' keyword to them). An example is:

.. |TF-A| replace:: :term:`TF-A`

The 'rst_prolog' variable in conf.py is used to inject this list of
replacements into each page. Terms must be surrounded with the pipe
character to be turned into links - this means that we can still
prevent certain terms from being linked if we don't want them to be.

Change-Id: I87010ed9cfa4a60011a9b4a431b98cb4bb7baa28
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

doc: Remove per-page contents lists ...

These are no longer needed as there will always be a table of contents
rendered to the left of every page.

Some of these lists can be quite long and, when opening a page, the
reader sees nothing but a huge list of contents! After this patch,
the document contents are front-and-centre and the contents are
nicely rendered in the sidebar without duplication.

Change-Id: I444754d548ec91d00f2b04e861de8dde8856aa62
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

doc: Reword document titles ...

This patch attempts to standardise the document titles as well as
adding titles to documents that were missing one. The aim is to
remove needless references to "TF-A" or "Trusted Firmware" in the
title of every document and to make sure that the title matches
with the document content.

Change-Id: I9b93ccf43b5d57e8dc793a5311b8ed7c4dd245cc
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

doc: Move content out of readme and create new index page ...

Previously the readme.rst file served as the entrypoint for the
documentation. With a Sphinx build the top-level document is set
to be index.rst as it contains the primary document index.

This patch moves some content from readme.rst into index.rst and
splits the license information out into license.rst.

Change-Id: I5c50250b81136fe36aa9ceedaae302b44ec11e47
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

doc: Move documents into subdirectories ...

This change creates the following directories under docs/
in order to provide a grouping for the content:

- components
- design
- getting_started
- perf
- process

In each of these directories an index.rst file is created
and this serves as an index / landing page for each of the
groups when the pages are compiled. Proper layout of the
top-level table of contents relies on this directory/index
structure.

Without this patch it is possible to build the documents
correctly with Sphinx but the output looks messy because
there is no overall hierarchy.

Change-Id: I3c9f4443ec98571a56a6edf775f2c8d74d7f429f
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

doc: Add minimal Sphinx support ...

Add the essentials for supporting a Sphinx documentation build:

- A makefile under docs/ to invoke Sphinx with the desired output
  format
- A Sphinx master configuration file (conf.py)
- A single, top-level index page (index.rst)
- The TF.org logo that is integrated in the the sidebar of the
  rendered output

Change-Id: I85e67e939658638337ca7972936a354878083a25
Signed-off-by: Paul Beesley <paul.beesley@arm.com>