[clng-tidy][NFC] Update documentation for readability-simplify-subscript-expr

Add release notes and mention ::std::span in documentation.
Change is related to #76116.

Author: PiotrZSL

clang-tools-extra/docs/ReleaseNotes.rst

@@ -458,6 +458,10 @@ Changes in existing checks
   <clang-tidy/checks/readability/non-const-parameter>` check to ignore
   false-positives in initializer list of record.
 
+- Improved :doc:`readability-simplify-subscript-expr
+  <clang-tidy/checks/readability/simplify-subscript-expr>` check by extending
+  the default value of the `Types` option to include ``std::span``.
+
 - Improved :doc:`readability-static-accessed-through-instance
   <clang-tidy/checks/readability/static-accessed-through-instance>` check to
   identify calls to static member functions with out-of-class inline definitions.