"Lemmy from Scratch" install steps don't mention PostgreSQL tuning like Docker does

[RocketDerp]

This is what Docker says:
https://github.com/LemmyNet/lemmy/blob/main/docker/docker-compose.yml#L108

We need to get that put into the Lemmy from Scratch steps.

Also, when the document is updated to Ubuntu 22.04 - consider which version of PostgreSQL should be recommended. As the "from Scratch" just goes with whatever Ubuntu provides by default (on my system 14.8, config file location: /etc/postgresql/14/main/postgresql.conf)

[RocketDerp]

ToDo: add more details to "Lemmy from Scratch" on upgrades. Tips such as: LemmyNet/lemmy#3269

[RocketDerp]

Ok, "from scratch" had some updates go in, but it still needs more work.

The NodeJS and Yarn install instructions are pretty outdated for Ubuntu 22.04.2 - and I think the Docker/Ansible installs are getting PostgreSQL 15, when the from-scratch steps yield PostgreSQL 14. It's extra steps to go beyond what Ubuntu distro provides and get 15 (and 16 is out shortly). 15 and 16 improve performance, and Lemmy is heavy on the database.

If someone does a 'virgin Ubuntu 22.04.2" system install following the page, please comment here on this issue with any problems / wrong information.

Also, I found this mentioned on another lemmy issue/pull-request discussion, it is a useful double-check when improving the front-scratch docs: https://i12bretro.github.io/tutorials/0675.html