Add commented out advice in _htaccess with respect to the KeepAlive Directive, taken from https://github.com/h5bp/html5-boilerplate/blob/master/.htaccess (license MIT)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@48182 b456876b-0849-0410-b77d-98878d47e9d5