Document module automated updates.

docs/development/module/updates.md

@@ -0,0 +1,11 @@
+# Automated updates
+
+farmOS modules may change and evolve over time. If these changes require
+updates to a farmOS database or configuration, then update logic should be
+provided so that users of the module can perform the necessary changes
+automatically when they update to the new version.
+
+This logic can be supplied via implementations of `hook_update_N()`.
+
+For more information, see the documentation for Drupal's
+[Update API](https://www.drupal.org/docs/drupal-apis/update-api/).

mkdocs.yml

@@ -10,6 +10,7 @@ nav:
       - Fields: development/module/fields.md
       - OAuth: development/module/oauth.md
       - Roles: development/module/roles.md
+      - Updates: development/module/updates.md
     - Environment:
       - Getting started: development/environment/index.md
       - Updating: development/environment/update.md