Merge branch '880-update-gitlab-readme-based-on-go-template-from-gluon' into 'master'

Update gitlab README and rolling upgrade job

Closes #880

See merge request platform-one/big-bang/bigbang!1002

chart/values.yaml

@@ -593,7 +593,7 @@ addons:
     git:
       repo: https://repo1.dso.mil/platform-one/big-bang/apps/developer-tools/gitlab.git
       path: "./chart"
-      tag: "5.3.1-bb.0"
+      tag: "5.3.1-bb.2"
 
     # -- Flux reconciliation overrides specifically for the Gitlab Package
     flux: {}