## What
This (admittedly massive) PR updates the "physical" documentation
structure and fixes url inconsistencies and SEO problems reported by
marketing. The main points are:
- remove or move directories : advanced, user_guide, deploy, api
- move the files contained within to the appropriate one of topics,
how-to, tutorials, or reference
- update internal doc links and product links to the content
- create client-side redirects for all the urls that have changed.
A number of the files have been renamed in small ways to better match
their url and to make them easier to find. Additionally, the top-level
api directory has been moved to /reference/api/legacy/unleash (see the
discussion points section for more on this).
## Why
When moving our doc structure to diataxis a while back, we left the
"physical' files lying where they were, because it didn't matter much to
the new structure. However, that did introduce some inconsistencies with
where you place docs and how we organize them.
There's also the discrepancies in whether urls us underscores or hyphens
(which isn't necessarily the same as their file name), which has been
annoying me for a while, but now has also been raised by marketing as an
issue in terms of SEO.
## Discussion points
The old, hand-written API docs have been moved from /api to
/reference/api/legacy/unleash. There _is_ a /reference/api/unleash
directory, but this is being populated by the OpenAPI plugin, and mixing
those could only cause trouble. However, I'm unsure about putting
/legacy/ in the title, because the API isn't legacy, the docs are. Maybe
we could use another path? Like /old-docs/ or something? I'd appreciate
some input on this.
## What
This PR fixes some broken links that have been hanging around in the
docs for what seems like a very long time.
## Why
As discovered by the link check in #1912, there are a fair few broken
links in the docs. Everyone hates broken links because it makes it
harder to understand what they were supposed to be pointing at.
## How
There are 3 types of links that have been fixed:
- Links that should have been internal but were absolute. E.g.
`https://docs.getunleash.io/path/article` that should have been
`./article.md`
- External links that have changed, such as Slack's API description
- GitHub links to files that either no longer exist or that have been
moved. These links generally pointed to `master`/`main`, meaning
they are subject to change. They have been replaced with permalinks
pointing to specific commits.
-----
* docs: fix slack api doc link
* docs: update links in migration guide
* docs: fix broken link to ancient feature schema validation
* docs: update links to v3 auth hooks
* docs: update broken link in the go sdk article
* Fix: use permalink for GitHub link
* docs: fix wrong google auth link
