DOCSP-44182-stable-release (#425)

* DOCSP-44182-stable-release

* edit stable/rapid release verbiage

Author: ajhuh-mdb

source/release-notes.txt

@@ -11,19 +11,15 @@ more information on types of MongoDB releases, see
 To see changes in {+c2c-product-name+} releases, see the following
 release notes.
 
-Upcoming Stable Release
-~~~~~~~~~~~~~~~~~~~~~~~
+Current Release
+~~~~~~~~~~~~~~~
 
 - :ref:`c2c-release-notes-1.8`
 
-Current Stable Release
-~~~~~~~~~~~~~~~~~~~~~~
+Previous Releases
+~~~~~~~~~~~~~~~~~
 
 - :ref:`c2c-release-notes-1.7`
-
-Previous Rapid Releases
-~~~~~~~~~~~~~~~~~~~~~~~
-
 - :ref:`c2c-release-notes-1.6`
 - :ref:`c2c-release-notes-1.5`
 - :ref:`c2c-release-notes-1.4`