Documentation: "git pull" does not have the "-m" option

Even though "--[no-]edit" can be used with "git pull", the
explanation of the interaction between this option and the "-m"
option does not make sense within the context of "git pull".  Use
the conditional inclusion mechanism to remove this part from "git
pull" documentation, while keeping it for "git merge".

Reported-by: Ivan Zakharyaschev
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/merge-options.txt

@@ -14,9 +14,12 @@ inspect and further tweak the merge result before committing.
 	further edit the auto-generated merge message, so that the user
 	can explain and justify the merge. The `--no-edit` option can be
 	used to accept the auto-generated message (this is generally
-	discouraged). The `--edit` (or `-e`) option is still useful if you are
-	giving a draft message with the `-m` option from the command line
-	and want to edit it in the editor.
+	discouraged).
+ifndef::git-pull[]
+The `--edit` (or `-e`) option is still useful if you are
+giving a draft message with the `-m` option from the command line
+and want to edit it in the editor.
+endif::git-pull[]
 +
 Older scripts may depend on the historical behaviour of not allowing the
 user to edit the merge log message. They will see an editor opened when