Docs: Document when alerts are updated

See #5907

docs/devel/alerts.rst

@@ -10,12 +10,22 @@ Currently the following is covered:
 
 * Duplicated source strings in translation files
 * Duplicated languages within translations
-* Merge or update failures in the source repository
-* Unused new base in component settings
+* Merge, update, or push failures in the repository
 * Parse errors in the translation files
-* Duplicate filemask used for linked components
-* Broken URLs
+* Billing limits (see :ref:`billing`)
+* Repository containing too many outgoing or missing commits
 * Missing licenses
+* Errors when running add-on (see :doc:`/admin/addons`)
+* Misconfigured monolingual translation.
+* Broken :ref:`component`
+* Broken URLs
+* Unused screenshots
+* Ambiguous language code
+* Unused new base in component settings
+* Duplicate filemask used for linked components
+
+The alerts are updated daily, or on related change (for example when
+:ref:`component` is changed or when repository is updated).
 
 Alerts are listed on each respective component page as :guilabel:`Alerts`.
 If it is missing, the component clears all current checks. Alerts can not be ignored,