Sort the toctree alphabetically

Author: stevepiercy

docs/backend/index.md

@@ -17,27 +17,27 @@ Insert introduction here.
 
 ```{toctree}
 :maxdepth: 2
+annotations
+behaviors
 configuration-registry
-control-panels
 content-types/index
-behaviors
-annotations
-vocabularies
+control-panels
 fields
-relations
-widgets
 global-utils
+indexing
+upgrading/index
+../plone.api/index
 portal-actions
-users-groups
+relations
 schemas
+search
 security
+sending-email
 subscribers
 traversal-acquisition
+users-groups
+vocabularies
+widgets
 workflows
-search
-indexing
 zodb
-../plone.api/index
-sending-email
-upgrading/index
 ```