Adds Hungarian (hu) to DOCUMENTATION_LANGUAGES in docs.py.

The Hungarian documentation was previously only partially translated, which might be the reason it was not included.

Now that the `docs.po` file is 100% translated, it would make sense to include `"hu": "hu"` in `DOCUMENTATION_LANGUAGES` so the Hungarian docs can be built and published as well.

Author: v1k70rk4

weblate_language_data/docs.py

@@ -22,4 +22,5 @@
     "de": "de",
     "nl": "nl",
     "ga": "ga",
+    "hu": "hu",
 }