The Hubot project looks to be abandoned; it hasn’t been updated in
years and its own installation instructions don’t work anymore.
Remove our special placement of Hubot alongside Zapier and IFTTT.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
api docs filenames are basically the operationId of their endpoint
in zulip.yaml with `_` replaced by `-`. But some operationIds have
changed, so change the affected filenames. Make changes in other
files accordingly.