docs/submittingpatches.html: correctly handle the <p> tag

As pointed out by the w3c validator.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Juan A. Suarez <jasuarez@igalia.com>

docs/submittingpatches.html

@@ -156,9 +156,11 @@ As mentioned at the begining, patches should be bisectable.
 A good way to test this is to make use of the `git rebase` command,
 to run your tests on each commit. Assuming your branch is based off
 <code>origin/master</code>, you can run:
+</p>
 <pre>
 $ git rebase --interactive --exec "make check" origin/master
 </pre>
+<p>
 replacing <code>"make check"</code> with whatever other test you want to
 run.
 </p>