Fix typo in docs

(miscomception ->misconception)

Backport of r1367778 from trunk resp.
r1367779. from 2.4.x.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1367780 13f79535-47bb-0310-9956-ffa450edef68