git-push.txt: fix grammar

While working on a blog post and using grammarly it suggested this
change.

Signed-off-by: Wesley Schwengle <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: waterkip

Documentation/git-push.txt

@@ -37,7 +37,7 @@ the default `<refspec>` by consulting `remote.*.push` configuration,
 and if it is not found, honors `push.default` configuration to decide
 what to push (See linkgit:git-config[1] for the meaning of `push.default`).
 
-When neither the command-line nor the configuration specify what to
+When neither the command-line nor the configuration specifies what to
 push, the default behavior is used, which corresponds to the `simple`
 value for `push.default`: the current branch is pushed to the
 corresponding upstream branch, but as a safety measure, the push is