Database connection configuration information is spreadout

### Contributions

- [X] I have read the contribution docs, and understand what's expected of me.

### Link to the page on docs.getdbt.com requiring updates

https://docs.getdbt.com/docs/core/connect-data-platform/redshift-setup
https://docs.getdbt.com/reference/resource-configs/redshift-configs
https://docs.getdbt.com/reference/database-permissions/redshift-permissions
https://docs.getdbt.com/docs/cloud/connect-data-platform/connect-redshift-postgresql-alloydb

### What part(s) of the page would you like to see updated?

As a dbt user I would like to know where to go to connect to a database so that a) I don't have to wonder what other pages I'm missing, b) I have a full outline of the content for the connector, and c) I'm not flipping through a bunch of doc tabs to set up a connection.

I would expect https://docs.getdbt.com/reference/resource-configs/redshift-configs to be my one stop shop as the central hub of anything related to Redshift connections.

I think it's fine that there are multiple pages as long as they link together. What's hard for me are things like:

* connect-redshift-postgresql-alloydb has no mention of ra3 nodes
* redshift-configs has no mention of ssh

I can't tell the whole list of things to consider in troubleshooting in one place. Having multiple pages that I keep scrolling up and down because I loose my place when I'm flipping tabs. I don't have a mental map(outline) of what content there is to reference.

### Additional information

I did not include the quick start guide, blog entries, or release notes links in here. As long as those are linked to from the other docs, that's all I would expect for those.

Also note, I totally know that keeping related pages connected and updated, yet not duplicative in an unmaintainable way, is one of the hardest things about doc maintenance. Hopefully the words I've used to frame it here are helpful.