Add helmRepoUrlRegex to the GitRepo docs

docs/gitrepo-add.md

@@ -68,6 +68,11 @@ spec:
   #
   # helmSecretName: my-helm-secret
   # 
+  # Helm credentials from helmSecretName will be used if the helm repository url matches this regular expression. 
+  # Credentials will always be used if it is empty or not provided
+  # 
+  # helmRepoUrlRegex: https://charts.rancher.io/*
+  #
   # To add additional ca-bundle for self-signed certs, caBundle can be
   # filled with base64 encoded pem data. For example:
   # `cat /path/to/ca.pem | base64 -w 0`