Adapt DocCardList for the Teleport docs site

[ptgott]

Partially addresses #29

Swizzle the Docusaurus-native DocCardList component and adapt it to suit the Teleport docs site. Since we prefer a more text-oriented approach to components, edit DocCardList to return a plain ul, rather than tiles.

Since the DocCardList component is a Docusaurus-native alternative to our remark-toc plugin, edit remark-toc to return a DocCardList instead of querying the filesystem to generate a table of contents. Once we replace all (!toc!) expressions with <DocCardList /> elements, we can remove remark-toc entirely.

Also make DocCardList an MDX component so docs authors don't need to add import statements to the top of a docs page.

[github-actions]

Amplify deployment status

Branch	Commit	Job ID	Status	Preview	Updated (UTC)
paul.gottschling/29-toc	3960825	7	❌FAILED	paul-gottschling-29-toc	2025-01-03 21:09:56

[ptgott]

Getting a bunch of errors like this in the Amplify preview build:

                                    Error: Can't render static file for pathname "/docs/ver/15.x/admin-guides/"
                                    at generateStaticFile (/codebuild/output/src1318284211/src/docs-website/node_modules/@docusaurus/core/lib/ssg/ssg.js:167:15)
                                    at processTicksAndRejections (node:internal/process/task_queues:105:5)
                                    at runNextTicks (node:internal/process/task_queues:69:3)
                                    at process.processImmediate (node:internal/timers:479:9)
                                    at async /codebuild/output/src1318284211/src/docs-website/node_modules/p-map/index.js:57:22 {
                                    [cause]: Error: no version doc found by id=/docs/ver/15.x/admin-guides/access-controls/access-controls
                                    at useDocById (server.bundle.js:34545:15)
                                    at /codebuild/output/src1318284211/src/docs-website/build/docs/__server/assets/js/17896441.a234c906.js:4881:61
                                    at Array.map (<anonymous>)
                                    at DocCardList (/codebuild/output/src1318284211/src/docs-website/build/docs/__server/assets/js/17896441.a234c906.js:4869:77)
                                    at Uc (server.bundle.js:3352:44)
                                    at Xc (server.bundle.js:3354:253)
                                    at Z (server.bundle.js:3360:89)
                                    at Xc (server.bundle.js:3354:481)
                                    at Z (server.bundle.js:3360:89)
                                    at Xc (server.bundle.js:3354:481)
                                    },

I'm guessing this is because the preview site doesn't include /docs/ in page paths, but I'll need to look into this more!