rebase docs: drop stray word in merge command description

Delete a misplaced word introduced by caafecfcf1 (rebase
--rebase-merges: adjust man page for octopus support, 2018-03-09).

Signed-off-by: Kyle Meyer <kyle@kyleam.com>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-rebase.txt

@@ -971,7 +971,7 @@ when the merge operation did not even start), it is rescheduled immediately.
 
 At this time, the `merge` command will *always* use the `recursive`
 merge strategy for regular merges, and `octopus` for octopus merges,
-strategy, with no way to choose a different one. To work around
+with no way to choose a different one. To work around
 this, an `exec` command can be used to call `git merge` explicitly,
 using the fact that the labels are worktree-local refs (the ref
 `refs/rewritten/onto` would correspond to the label `onto`, for example).