Add "Daemon" entry to Moneropedia

Interaction with a daemon is a prerequisite to using the Monero software. Thus, the daemon is a pretty central cencept and probably ought to have a Moneropedia entry.

Some highlights to include (and there are probably other important ones - suggestions?):

purpose
trusted vs untrusted
remote vs local
basic command line usage?

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information