Docs-14996 add obsolete build variate note (#371)

* DOCS-14996 add platform no longer supported messaging

* add 5.1.2.rst reference

* moved 5.1 note down to bottom of page

* *

* add EE CE mentions and release note mention

* *

* **

* header - remove

* change header type for community edition on 5.1.2 page

Author: ianf-mongodb

source/includes/changelogs/releases/5.1.2.rst

@@ -83,3 +83,13 @@ Internals
 - :issue:`SERVER-62243` Wait for vector clock document majority-commit without timeout
 - :issue:`WT-8241` Skip value return for largest key
 
+Platform Support
+~~~~~~~~~~~~~~~~
+
+Starting in MongoDB 5.1.2 the following platforms are no longer 
+supported.
+
+Community Edition
+`````````````````
+
+- :abbr:`RHEL (Red Hat Enterprise Linux)`-72-s390x

source/release-notes/5.1-compatibility.txt

@@ -183,12 +183,22 @@ will receive an error message like the following:
    :: caused by :: network error while attempting to run command
    'isMaster' on host '127.0.0.1:27017'
 
+Platform Support
+----------------
+
+Starting in MongoDB 5.1.2 the following platforms are no longer 
+supported.
+
+Community Edition
+~~~~~~~~~~~~~~~~~
+
+- :abbr:`RHEL (Red Hat Enterprise Linux)`-72-s390x
+
 .. _5.1-compatibility-enabled:
 
 5.1 Feature Compatibility
 -------------------------
 
 Some features in 5.1 require the 5.1 binaries and the
 :ref:`featureCompatibilityVersion <view-fcv>` (fCV) must also be set to
-5.1. These features include:
-
+5.1. These features include:

source/release-notes/5.1.txt

@@ -191,6 +191,18 @@ Starting in MongoDB 5.1, you can use the :dbcommand:`collMod` database
 command to add the ``expireAfterSeconds`` option to an existing
 single-field non-TTL index.
 
+
+Platform Support
+----------------
+
+Starting in MongoDB 5.1.2 the following platforms are no longer 
+supported.
+
+Community Edition
+~~~~~~~~~~~~~~~~~
+
+- :abbr:`RHEL (Red Hat Enterprise Linux)`-72-s390x
+
 .. _5.1-rel-notes-general:
 
 General Improvements