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)

Change-Id: I4847f655f72c3ce4fe1f0d197b00167e499dd658
Signed-off-by: Kristal Dale <kristal.dale@intel.com>

doc/source/index.rst

@@ -1,11 +1,8 @@
+==========================
 stx-upstream Documentation
 ==========================
 
-StarlingX Upstream Packaging
-
-.. toctree::
-   :maxdepth: 2
-   :caption: Contents:
+This is the documentation for StarlingX upstream packaging.
 
 Release Notes
 -------------
@@ -16,7 +13,7 @@ Release Notes
    Release Notes <https://docs.starlingx.io/releasenotes/stx-upstream>
 
 Links
-=====
+-----
 
 * Source: `stx-upstream`_
 * Code Review: `Gerrit`_
@@ -25,9 +22,3 @@ Links
 .. _stx-upstream: https://git.starlingx.io/cgit/stx-upstream/
 .. _Gerrit: https://review.openstack.org/#/q/project:openstack/stx-upstream
 .. _Storyboard: https://storyboard.openstack.org/#!/project/openstack/stx-upstream
-
-Indices and tables
-==================
-
-* :ref:`search`
-* :ref:`genindex`

releasenotes/source/index.rst

@@ -1,3 +1,4 @@
+==========================
 stx-upstream Release Notes
 ==========================
 
@@ -5,9 +6,3 @@ stx-upstream Release Notes
    :maxdepth: 2
 
    unreleased
-
-Search
-------
-
-:ref:`search`
-