Add Crowdin configuration file (#439)

crowdin.yml

@@ -0,0 +1,27 @@
+base_path: "."
+base_url: "https://neoforged.api.crowdin.com"
+
+# For interacting with Crowdin locally (via CLI), set these environment variables to their proper values
+project_id_env: "NEOFORGE_CROWDIN_PROJECT_ID"
+api_token_env: "NEOFORGE_CROWDIN_API_TOKEN"
+
+# Preserve directory structure (required by the use of the 'dest' field below)
+preserve_hierarchy: true
+
+# Prevent Crowdin-created commits from automatically triggering builds
+commit_message: "[ci skip]"
+# Automatically label PRs made by Crowdin
+pull_request_labels: [ "l10n" ]
+
+files:
+    -   source: "/src/main/resources/assets/neoforge/lang/en_us.json"
+        # Unfortunately, Crowdin doesn't have a placeholder which matches Minecraft's expected naming scheme: underscores
+        # with lowercase letters (since resource location are required to be fully lowercase).
+        #
+        # To make up for this unfortunate defect, **in the Crowdin interface**, we specify custom language mappings for
+        # the "%locale_with_underscore%" placeholder, converting the uppercase to lowercase in the original value.
+        #
+        # If you are adding a new language to the Crowdin project,
+        # ** MAKE SURE YOU ADD THE APPROPRIATE CUSTOM LANGUAGE MAPPING FOR THE PLACEHOLDER. **
+        translation: "/src/main/resources/assets/neoforge/lang/%locale_with_underscore%.%file_extension%"
+        dest: "/messages.%file_extension%"