ci: create a config file for the crowdin github Action

As written in the manual, create crowdin.yml with the config info
for the Crowdin github Action.

Manual location: https://github.com/marketplace/actions/crowdin-action

Author: shpaass

crowdin.yml

@@ -0,0 +1,19 @@
+# This file has the info necessary for the setup of the Crowdin github Action.
+# The info was taken from the page of the github Action: https://github.com/marketplace/actions/crowdin-action
+
+# By default, the Action will look for the crowdin.yml file in the root of the repository, so I put this file in there.
+# Feel free to discuss moving it elsewhere if you can think of a better location.
+# You can specify a different path using the "config" option in this file.
+
+"project_id_env": "CROWDIN_PROJECT_ID"
+"api_token_env": "CROWDIN_PERSONAL_TOKEN"
+"base_path": "."
+
+"preserve_hierarchy": true
+
+"files": [
+  {
+    "source": "locales/en.yml",
+    "translation": "locales/%two_letters_code%.yml"
+  }
+]