Make auto-generated docs for TerriaJS version 8

[steve9164]

I have a half-auto generated docs process for TerriaJS version 8. It's roughly:

• Build and run TerriaMap running the mobx-generate-docs TerriaMap branch
• Copy the downloaded zip of markdown files and unzip them into a clone of terriajs running the mobx-generate-docs terriajs branch
• Run gulp docs (with a Python environment that has correct installed dependencies)
• Deploy to static hosting site

But I haven't run this for about 6 months. It's time to automate this fully. There is some work on https://github.com/TerriaJS/TerriaMap/blob/mobx-generate-docs/index.js to generate markdown from the Trait system. This has been integrated into the old docs and deployed here: https://mobx-terria-docs.surge.sh/connecting-to-data/catalog-items/ (with the help of some terriajs changes here.

The docs generation should now be able to run in node (and without TerriaMap) now that the model & traits system can be built for and run in node (as of ~6 months ago).

Rough task list:

• Move markdown generation code from TerriaMap's index.js to somewhere in terriajs and use terriajs running on node
• Change from using a list of model types to using all registered catalog items/groups/references. Or something
• Make the command gulp docs runnable again. It should probably build terriajs using the terriajs-node (tsc -b tsconfig-node.json) and then generate markdown files from models & traits.
• Add gulp docs back into CI

[soyarsauce]

Once this is ready, we should have a v8 version of docs.terria.io (in parallel)

Or option 2 - swap docs with dropdown

[soyarsauce]

Don't need decision now - but things to consider:

• seo / multiple versions of duplicate content / confusing versioning
• popular ways of dealing with this? e.g. kubernetes

[soyarsauce]

Once we are closer to the v8 release, we make the v8 docs the main docs, and host v7 docs elsewhere with a link saying if you need old docs, go here - robots meta noindex meta tags to not be indexed.

Host the v8 docs somewhere - @steve9164 to speak w/ @soyarsauce & look into auto hosting v8 docs so we can get it out

[soyarsauce]

Unsure if this will make the oct communications

[steve9164]

Closed as there's other tickets tracking this work. See especially #4666.