Move config schema reference to md format

[RomneyDa]

Created new config schema reference page at https://docs.continue.dev/customize/config in md format

Note, accidentally pushed the first half of this PR directly to dev a bit back, including

• remove config_schema from docs
• initial config.md creation was causing some test to fail for a while

Checklist

• [x] The base branch of this PR is dev, rather than main
• [x] The relevant docs, if any, have been updated or created

[Patrick-Erichsen]

Commit that I pushed up is primarily to move this all under a "References" nav item.

I also attempted to make the /customize/overview page into a category (like this https://docs.continue.dev/customize/model-providers) for the sidebar items under the Customize nav item, but it doesn't seem to be possible. Category sidebar items have a dropdown toggle by default that contain all of the items associated to the category, which are what's used to generate the preview cards. See the docs here: https://docusaurus.io/docs/sidebar/items#sidebar-item-category

So, we will need to either create a custom .mdx doc that imports the relevant Card component and manually map them, or just make a regular markdown page of some sort. I would opt for a simple markdown approach since creating anything custom is pretty involved in Docusaurus, e.g. https://docusaurus.community/knowledge/component-library/new/Card/

[sestinj]

@RomneyDa @Patrick-Erichsen I made a few tweaks and then in a second commit I moved the top-level discussion away from the Reference page and into a "Deep Dive" called "Ways to configure". I think we had decided on this here: https://www.notion.so/continuedev/config-json-markdown-brainstorm-1271d55165f780d5b704d52c7cd1998c?pvs=4#1271d55165f7809ab183ce57bd02dd89

But otherwise I'm happy with anyone else clicking the merge button once you feel this is good