docs: simplify each section title

Now that we merged into one doc, it makes the nav looks nicer.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210323074704.4078381-1-marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>

docs/devel/index.rst

@@ -1,8 +1,8 @@
 .. This is the top level page for the 'devel' manual.
 
 
-QEMU Developer's Guide
-======================
+Developer Information
+=====================
 
 This manual documents various parts of the internals of QEMU.
 You only need to read it if you are interested in reading or

docs/interop/index.rst

@@ -1,8 +1,8 @@
 .. This is the top level page for the 'interop' manual.
 
 
-QEMU System Emulation Management and Interoperability Guide
-===========================================================
+System Emulation Management and Interoperability
+================================================
 
 This manual contains documents and specifications that are useful
 for making QEMU interoperate with other software.

docs/specs/index.rst

@@ -1,8 +1,8 @@
 .. This is the top level page for the 'specs' manual
 
 
-QEMU System Emulation Guest Hardware Specifications
-===================================================
+System Emulation Guest Hardware Specifications
+==============================================
 
 
 Contents:

docs/system/index.rst

@@ -1,8 +1,8 @@
 .. This is the top level page for the 'system' manual.
 
 
-QEMU System Emulation User's Guide
-==================================
+System Emulation
+================
 
 This manual is the overall guide for users using QEMU
 for full system emulation (as opposed to user-mode emulation).

docs/tools/index.rst

@@ -1,8 +1,8 @@
 .. This is the top level page for the 'tools' manual
 
 
-QEMU Tools Guide
-================
+Tools
+=====
 
 
 Contents:

docs/user/index.rst

@@ -1,8 +1,8 @@
 .. This is the top level page for the 'user' manual.
 
 
-QEMU User Mode Emulation User's Guide
-=====================================
+User Mode Emulation
+===================
 
 This manual is the overall guide for users using QEMU
 for user-mode emulation.  In this mode, QEMU can launch