- Add some links.

- Remove the space in "character set" in the syntax of ProxyFtpDirCharset to avoid confusion (it is 1 parameter only)
- Use the correct syntax for the "default" values, so that they are parsed and correctly displayed in 'quickreference'
- Remove extra [] when directive's parameter are required

- correct the default password: apache-proxy@ instead of apache_proxy@.
This was silently changed in r88745, 17 years ago!

(r1838313 in trunk + some style to synch 2.4.x and trunk)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1838314 13f79535-47bb-0310-9956-ffa450edef68