Add docs for connecting mathesar to local db

[Anish9901]

Fixes #2571

Documentation about how to connect Mathesar to a Postgres DB running locally on a host machine (i.e. DB outside the docker container).

There doesn't seem to be an elegant approach we can take for connecting Mathesar to a host db without fiddling around with a bunch of internal Postgres files on the host system namely the postgresql.conf & pg_hba.conf. If someone really wants to connect Mathesar to their local db the steps are clearly documented in this PR.

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[mathemancer]

The steps are clear enough, and worked for me. I think this makes some dubious assumptions, however, and it's oddly placed in the overall documentation.

• If someone is just following the install script, they will get blocked up before making it to a running system (if they want to connect)
• I'm not sure about the placement in the navigation on the left.

I think this needs to be linked from the main install via docker compose page with some kind of 'note' or 'warning' style, as some kind of optional prerequisites specific to this type of installation. Will it be possible to figure out the network settings before running the installer? If not, that makes things even more difficult.

[mathemancer]

I think this looks good. Thank you!

[seancolsen]

I happened to notice that this new docs page is in in the guide but not in the guide's nav menu. @Anish9901 can you edit docs/mkdocs.yml and add a link to this new page somewhere within nav? @mathemancer It would be good to check for this when reviewing PRs too.

[Anish9901]

@seancolsen it was actually @mathemancer suggestion to not put the guide in the nav menu as it might confuse users and might lead them to not be able to complete the installation process using the install script which is a requirement for following the steps suggested in this guide.

[seancolsen]

Oh sorry -- I should have read his comment before making mine. Interesting. Having a page in the guide which is not in the nav menu feels very weird to me. Like, if you navigate to that page, you should be able to use the nav menu to understand your current context within the rest of the documentation and to navigate back to other pages. Publishing it outside the nav turns the page into a sort of dead end. It also makes the page harder for readers to find.

Having read Brent's comment a few times, I still don't understand the reason for not putting this in the nav -- I think maybe because I don't understand the docs content well enough. @mathemancer could we address your concerns by placing some sort of disclaimer at the top of this page?