Fix beta builds

The extension's beta name strings were missing.

Change-Id: I0245671c627aced507a9c6460bd6b852aaf1ebaa
diff --git a/src/_locales/pl/messages.json b/src/_locales/pl/messages.json
index da4f205..c6e16e9 100644
--- a/src/_locales/pl/messages.json
+++ b/src/_locales/pl/messages.json
@@ -56,6 +56,9 @@
    "name": {

       "message": "Screen Capture"

    },

+   "name_beta": {

+      "message": "Screen Capture (beta)"

+   },

    "ok": {

       "message": "OK"

    },