Include pgbouncer by default

Just throwing this out there.

Seems like it could be a nice inclusion to have by default. I imagine that this has already been considered and there is some reason to not include it, like it is not good on resources for small servers?

Would be really fantastic if there were some noob-friendly instructions for adding it otherwise.

At the size of a site that is running our noob-friendly all in one docker instance the complexity trade-off of pgBouncer is not really worth for us.

Now if you are running a normal dedicated PostgreSQL service complete with pgBoucer, you can point Discourse to the pgBouncer service by following Running Discourse with a separate PostgreSQL server