[DOCS] Add descriptions to the spec files for internal and blocked APIs #2273
Description
Tracking issue for track doc updates to specification files. To prevent duplicated work, leave your name beside a namespace/API you start working on.
Related to #964.
Serverless plan: https://docs.google.com/spreadsheets/d/1xFrpFP1dARey8A1QkAoC7JJCGhAZFexMLpRTeY9PAos/
- autoscaling BLOCKED
- ccr BLOCKED
- dangling_indices BLOCKED
- features BLOCKED
- fleet INTERNAL
- ilm BLOCKED
- license BLOCKED (GET license is addressed)
- migration BLOCKED
- monitoring BLOCKED
- searchable_snapshots INTERNAL
- security most of the endpoints are addressed, the rest is INTERNAL
- shutdown BLOCKED
- slm BLOCKED
- snapshot INTERNAL
- ssl INTERNAL
- watcher not working on serverless at least for now
- xpack INTERNAL