sync table(5) with reality

sync table(5) with reality

There are two different parser for table(5)s with different edge cases.
Adjust the documentation to what the strictier of the two (smtpd
internal parser) accepts, even if makemap(8) allows for more.

In particular, adjust the description for the comments (that cannot be
'anywhere in the file'), document the special comment @list and mention
that splitting is done on the colon character too.

ok and many improvements from jmc@