Update SSLPassPhraseDialog directive docs to correctly describe the

current behavior for "exec"-type programs in 2.4.x, at least.
The new argument structure is a consequence of r1573360 (backport
to 2.4.8 [unreleased]).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1585902 13f79535-47bb-0310-9956-ffa450edef68