Documentation update
- make it clear that you have to have an existing repo to clone
- don't try to put the same key in different directories
- explain the .mercurial-server file.
# Log every push and pull to the servelog
[hooks]
changegroup.aaaaa_servelog = python:mercurialserver.servelog.hook
outgoing.aaaaa_servelog = python:mercurialserver.servelog.hook