Docs: add mpm_prefork config for Apache 2.4 systems

Docs: add mpm_prefork config for Apache 2.4 systems

We had only documented the Apache 2.2 stanzas for mpm_prefork, so include a
section for 2.4 that uses MaxRequestWorkers and MaxConnectionsPerChild. Given
the memory leaks that we have seen, suggest lower settings for these two values
(assuming that most sites will be serving a public catalogue instead of using a
separate discovery layer).

Also fix the weird formatting where Debian instructions were indented under a
Fedora section.

Also use dots for ordered bullets instead of renumbering all of the bullets
again.

Signed-off-by: Dan Scott <dscott@laurentian.ca>