docs: Document submission_over_tls_address option

The submission_over_tls_address configuration option has existed for a
long time, but was not properly documented.

This patch adds it to the manpage, as well as printing it in the
configuration output on startup.
1 job for upstream in 4 minutes and 41 seconds
latest
Status Job ID Name Coverage
  Test
failed #255109
integration_test

00:04:41

 
Name Stage Failure
failed
integration_test Test
ok  	blitiri.com.ar/go/chasquid/internal/tlsconst	0.003s
? blitiri.com.ar/go/chasquid/internal/trace [no test files]
ok blitiri.com.ar/go/chasquid/internal/userdb 0.593s
setsid -w ./test/run.sh
t-01-simple_local ...
msmtp: cannot locate host testserver: Name or service not known
msmtp: could not send mail (account default from msmtprc)
make: *** [Makefile:41: test] Error 68
ERROR: Job failed: exit code 2