Clean up and standardize landing pages

doc index.rst:
1. Update intro sentence to read as a complete sentence
2. Remove unused toctree
3. Correct heading levels (impacting side nav and correct rendering
of content)
4. Remove "Indices and Tables" section: genindex page not used,
search searches
only index (not useful here)

releasenotes index.rst:
1. Standardize page title reST markup
2. Remove search (make consistent with other openstack release note
pages)

Story: 2004737
Task: 28802

Change-Id: I781d2fb0ef51ae952c5e6707ab38f1fca237e5b5
Signed-off-by: Kristal Dale <kristal.dale@intel.com>

doc/source/index.rst

@@ -1,11 +1,9 @@
+=====================
 stx-gui Documentation
 =====================
 
-StarlingX Horizon plugins for new StarlingX services
-
-.. toctree::
-   :maxdepth: 2
-   :caption: Contents:
+The StarlingX stx-gui project provides Horizon plugins for new StarlingX
+services.
 
 Release Notes
 -------------
@@ -16,7 +14,7 @@ Release Notes
    Release Notes <https://docs.starlingx.io/releasenotes/stx-gui>
 
 Links
-=====
+-----
 
 * Source: `stx-gui`_
 * Code Review: `Gerrit`_
@@ -25,9 +23,3 @@ Links
 .. _stx-gui: https://git.starlingx.io/cgit/stx-gui/
 .. _Gerrit: https://review.openstack.org/#/q/project:openstack/stx-gui
 .. _Storyboard: https://storyboard.openstack.org/#!/project/openstack/stx-gui
-
-Indices and Tables
-==================
-
-* :ref:`search`
-* :ref:`genindex`

releasenotes/source/index.rst

@@ -1,3 +1,4 @@
+=====================
 stx-gui Release Notes
 =====================
 
@@ -5,8 +6,3 @@ stx-gui Release Notes
    :maxdepth: 2
 
    unreleased
-
-Search
-------
-
-:ref:`search`