Consider dropping xrd.network keepalive from example configs #58

According to some docs, for example https://indico.cern.ch/event/523410/contributions/2355670/attachments/1367325/2071860/XWS-Tokyo-Status.pdf, keepalive is the default in XRootD for about 10 years.

So any upcoming EOS release can savely assume keepalive being already enabled, right?

So I'd suggest to just remove xrd.network keepalive from

• doc/diopside/manual/configuration.rst
• misc/etc/xrd.cf.fst
• misc/etc/eos/config/fst/fst

One could argue that maybe some admins want to set the kaparms suboption? I think, that's advanced use (and it's currently not even mentioned in the eos repo!).