[Server] Make all server requests appear in the doc index.

src/plugins/server/request.ml

@@ -307,7 +307,9 @@ let register_sig (type a b) (s : (a,b) signature) (process : rq -> a -> b) =
     doc_input s.input @
     doc_output s.output
   in
-  let _ = Doc.publish ~page:s.page ~name:s.name ~title description [] in
+  let _ =
+    Doc.publish ~page:s.page ~name:s.name ~title ~index:[s.name] description []
+  in
   Main.register s.kind s.name processor ;
   s.defined <- true