passwords enabled by default

Recently, while testing my changes to entrypoint.sh in Docker, I noticed
that you cannot import or export passwords via the servers.json file. You
can get around this by setting the PassFile option in servers.json, but
that still doesn't work correctly. For me to make this work, I had to also
set the `PGPASSFILE` to the full path location of the pgpass file generated
for me by Helm.

To clarify, I know how many servers I want to connect to and how to find
their passwords in Kubernetes via their secret, and I use Helm to stitch
all of that together into a pgpass file that psql and pgadmin4 can use to
connect to the servers without user intervention.

The presence of the pgpass file and the reference to that file in the
servers.json was not enough to allow pgadmin4 to connect to the servers, I
also had to set `PGPASSFILE` in my Helm chart to make this work.

This seems like another good ticket, no? I know where to add them and I'll
put a patch in place, but I could sure use a little bit of guidance on the
copy portion of the documentation. I know why it works for me, but would
anyone conceivably use this in a non-Dockerized deployment?

Thanks,
Andrew