Merge branch 'fix-semgrep-docs' into 'master'

Mention that semgrep is an experimental feature

See merge request gitlab-org/gitlab!56898

doc/user/application_security/sast/index.md

@@ -517,6 +517,7 @@ removed, or promoted to regular features at any time.
 Experimental features available are:
 
 - Enable scanning of iOS and Android apps using the [MobSF analyzer](https://gitlab.com/gitlab-org/security-products/analyzers/mobsf/).
+- Enable the [semgrep analyzer](https://gitlab.com/gitlab-org/security-products/analyzers/semgrep/).
 
 #### Enable experimental features