Refresh parts of the proxy docs, with special attention to clarifying the

security issues in forward and reverse proxy situations.

- Remove the historical narrative in the top section and simply state
the facts.

- Remove the table of contents, since we already generate one for the sidebar.

- Rewrite the forward vs reverse section to be clear on the purpose of
the two types of proxy.

- Add some basic examples of each type of proxy to replace the example removed
from the default config file.

- Add a note to the access control section on forward versus reverse proxys,
and also add a reference to mod_access that got removed at some point.

- Add a warning to the ProxyPass docs that ProxyRequests should be off.

- Shorten some section titles.

I did not add the
ProxyBlock :25
because I don't have a proxy server to test it on at the moment.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@100759 13f79535-47bb-0310-9956-ffa450edef68