selectrum: document embark-act binding

Also add `C-c C-e` TODO

modules/completion/selectrum/TODO.org

@@ -13,6 +13,7 @@ Need to get it to work for other selectrum commands such =SPC h f=.
     (map! :map minibuffer-local-map "C-SPC" #'embark-default-action)))
 #+end_src
 gets us close but moves the cursor to the new screen which is undesirable.
+** TODO =C-C C-e= wgrep fun
 * PROJ List of things needed for Ivy parity
 ** TODO Icons
 https://github.com/minad/marginalia/issues/59