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>

docs/acknowledgements.rst

+Contributor Acknowledgements
+============================
+
 **Note: This file is only relevant for legacy contributions, to acknowledge the
 specific contributors referred to in "Arm Limited and Contributors" copyright
 notices. As contributors are now encouraged to put their name or company name
 directly into the copyright notices, this file is not relevant for new
 contributions.**
 
-Contributor Acknowledgements
-============================
-
 Companies
 ---------
 

docs/change-log.rst

-Trusted Firmware-A Release Notes
-================================
+Change Log & Release Notes
+==========================
 
 This document contains a summary of the new features, changes, fixes and known
 issues in each release of Trusted Firmware-A.

docs/components/arm-sip-service.rst

-Arm SiP Service
-===============
+Arm SiP Services
+================
 
 This document enumerates and describes the Arm SiP (Silicon Provider) services.
 

docs/components/exception-handling.rst

-Exception Handling Framework in Trusted Firmware-A
-==================================================
-
-
-
+Exception Handling Framework
+============================
 
 .. contents::
     :depth: 2

docs/components/firmware-update.rst

-Trusted Firmware-A - Firmware Update design guide
-=================================================
-
-
-
+Firmware Update (FWU)
+=====================
 
 .. contents::
 

docs/components/platform-interrupt-controller-API.rst

-Platform Interrupt Controller API documentation
-===============================================
-
-
+Platform Interrupt Controller API
+=================================
 
 .. contents::
 

docs/components/ras.rst

-RAS support in Trusted Firmware-A
-=================================
-
-
+Reliability, Availability, and Serviceability (RAS) Extensions
+==============================================================
 
 .. contents::
     :depth: 2

docs/components/secure-partition-manager-design.rst

-*******************************
-Secure Partition Manager Design
-*******************************
-
-
+Secure Partition Manager
+************************
 
 .. contents::
 

docs/components/xlat-tables-lib-v2-design.rst

-Translation Tables Library Design
+Translation (XLAT) Tables Library
 =================================
 
-
-
-
 .. contents::
 
 

docs/design/auth-framework.rst

-Abstracting a Chain of Trust
-============================
-
-
-
+Authentication Framework & Chain of Trust
+=========================================
 
 .. contents::
 

docs/design/firmware-design.rst

-Trusted Firmware-A design
-=========================
-
-
-
+Firmware Design
+===============
 
 .. contents::
 

docs/design/interrupt-framework-design.rst

-Trusted Firmware-A interrupt management design guide
-====================================================
-
-
-
+Interrupt Management Framework 
+==============================
 
 .. contents::
 

docs/design/psci-pd-tree.rst

-PSCI Power Domain Tree design
-=============================
-
-
-
+PSCI Power Domain Tree Structure
+================================
 
 .. contents::
 

docs/design/reset-design.rst

-Trusted Firmware-A reset design
-===============================
+CPU Reset
+=========
 
 
 

docs/design/trusted-board-boot.rst

-Trusted Board Boot Design Guide
-===============================
+Trusted Board Boot
+==================
 
 
 

docs/getting_started/porting-guide.rst

-Trusted Firmware-A Porting Guide
-================================
-
-
+Porting Guide
+=============
 
 .. contents::
 

docs/getting_started/rt-svc-writers-guide.rst

-Trusted Firmware-A EL3 runtime service writer's guide
+EL3 Runtime Service Writer's Guide
 =====================================================
 
 

docs/getting_started/user-guide.rst

-Trusted Firmware-A User Guide
-=============================
-
-
-
+User Guide
+==========
 
 .. contents::
 

docs/index.rst

@@ -14,8 +14,8 @@ Trusted Firmware-A Documentation
    perf/index
    security_advisories/index
    change-log
-   maintainers
    acknowledgements
+   maintainers
    license
 
 Trusted Firmware-A (TF-A) provides a reference implementation of secure world

docs/maintainers.rst

-Trusted Firmware-A maintainers
-==============================
+Maintainers
+===========
 
 Trusted Firmware-A (TF-A) is an Arm maintained project. All contributions are
 ultimately merged by the maintainers listed below. Technical ownership of some