Need to document expected expected good log messages for pods

[DougReeder]

Is your feature request related to a problem? Please describe.
It's hard to debug a cluster that's misbehaving using the pod logs, without knowing what messages are normal and which indicate a problem that should be addressed

Describe the solution you'd like
For each pod log, what messages are expected, especially ones that sound like an error. Also, for log messages that indicate a common problem, the approach to fixing it.

For example:
"When pgbouncer is first operational, this will be logged: 'LOG process up: PgBouncer 1.15.0, libevent 2.1.12-stable (epoll), adns: udns 0.4, tls: OpenSSL 1.1.1l 24 Aug 2021'"
"It's normal to have multiple 'login attempt:' messages.

We need to document if these ambiguous log messages are good or bad:
"LOG C-0x7fad0476b0e0: retdb/[email protected]:50080 closing because: client close request (age=10s)"
"LOG C-0x7fad0476b310: retdb/[email protected]:50090 closing because: client unexpected eof (age=496s)"

Describe alternatives you've considered
It would be nice if the logs were self-explanatory, but we don't control software like pgbouncer.

Additional context