migrate documentation to cylc-doc

[oliver-sanders]

Note Don't Merge I'm thinking we should merge this after 8.0a3 release so we get time to test the release mechanism on the offline docs.

• Removes the documentation from this site, linking it to the cylc-doc gh-pages.
• Adds a 404 page which uses Javascript to redirect present users with a redirect notice with a link to the new docs.
• Migrates the publication section from documentation.md to the homepage.
• Migrates the FAQ to its own page.
• Deletes the screenshot page (we may want to restore, but where to).

Note: Pre merge the default documentation version should changed to 7.9.x on the cylc-doc gh-pages branch

Done

[oliver-sanders]

Kinda hard to test as it won't work right unless it's hosted on an organisational account as the paths differ.

[hjoliver]

Note Don't Merge

(Converted to Draft PR, to prevent merging for now)

[hjoliver]

Removes the documentation from this site, linking it to the cylc-doc gh-pages.

Note that users have gotten grumpy several times in the past if we remove the single-page build (because sphinx search is rubbish) or break existing links posted to the forum (most recently, just last week!). So I wonder if we should leave the existing docs on the web site for a while, as we transition to cylc-doc, to cover existing usage?

[oliver-sanders]

Can do., though all 404 pages will redirect to the new docs.

(note single page build is not currently possible with the new docs as some of the auto-documented pages get cut-off)

[hjoliver]

(note single page build is not currently possible with the new docs as some of the auto-documented pages get cut-off)

Ah, I was wondering about that.

[oliver-sanders]

Removed the commit that removed the old docs.

[oliver-sanders]

The old documentation page is still in there but not linked to from the main nav.