Merge branch 'docs/fix-sast-use-cases' into 'master'

Fix SAST use cases in documentation

See merge request gitlab-org/gitlab-ee!8979

doc/user/project/merge_requests/sast.md

@@ -23,11 +23,10 @@ request widget area.
 
 ## Use cases
 
-- Your application is using an external (open source) library, locked to a
-  specific version (e.g., via `Gemfile.lock`) and the version is known to be
-  vulnerable.
 - Your code has a potentially dangerous attribute in a class, or unsafe code
   that can lead to unintended code execution.
+- Your application is vulnerable to cross-site scripting (XSS) attacks that can
+  be leveraged to unauthorized access to session data
 
 ## Supported languages and frameworks