allow for additional container environment variables (#16)

Co-authored-by: Jasper Orschulko <Jasper.Orschulko@irisgmbh.de>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/16
Reviewed-by: luhahn <luhahn@noreply.gitea.io>
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>

values.yaml

@@ -55,6 +55,9 @@ tolerations: []
 affinity: {}
 
 statefulset:
+  env: []
+    # - name: VARIABLE
+    #   value: my-value
   terminationGracePeriodSeconds: 60
 
 persistence: