Properly document PGBouncer calculation behavior on Software

[jwitz]

Issue Type

Missing content for an existing feature

Links to Affected Docs

https://docs.astronomer.io/software/release-notes#automatic-pgbouncer-connection-scaling

The Issue or Context

PGBouncer calculation has impact on how many database connections customers can make. To be honest, I'm not the best one to write this issue. I barely understand this feature. That's why it needs documented!

Fix or Proposed Change

No response

Additional Notes

No response

Required Reviewers

No response