DOCSP-43248-upgrade-catch2-library (#90)

* DOCSP-43248-upgrade-catch2-library

* fix copy

* rewording

Author: gmiller-mdb

source/upgrade.txt

@@ -220,6 +220,9 @@ The v3.11 driver introduces the following breaking changes to the build system:
 
 - Drops support for {+mdb-server+} v3.6.
 - Requires MongoDB C Driver v1.28.0 or later.
+- If the ``ENABLE_TESTS`` configuration option is set to ``ON``, C++14 or later
+  is required. You can opt out of the C++14 requirement by disabling tests with 
+  ``ENABLE_TESTS=OFF`` during CMake configuration.
 
 ABI Breaking Changes in v3.11
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