Second attempt at improving indexing in control.texi

* doc/lispref/control.texi (Processing of Errors): Improve indexing by
adding the word form "handle" in addition to "handling".  With thanks
to Eli Zaretskii.
1 job for emacs-27 in 61 minutes (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #6049
test-all

01:01:00