Remove redundant slash from example - mod_proxy doc

Submitted by: nisbet-hubbard <87453615+nisbet-hubbard@users.noreply.github.com>

Github: closes #378


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1915459 13f79535-47bb-0310-9956-ffa450edef68
2 files changed