Update docs for trigger-when-paused.

[hjoliver]

Companion for cylc/cylc-flow#6192 cylc/cylc-flow#6499

@oliver-sanders - I still need to update the intervention gif animation. Is it possible for you to advise on window size etc. so that I end up with a similar look to your originals, or do I just have to experiment with that?

TODO:

• update the intervention gif animation

Requirements check-list

• I have read CONTRIBUTING.md and added my name as a Code Contributor.

[oliver-sanders]

@oliver-sanders - I still need to update the intervention gif animiation. Is it possible for you to advise on window size etc. so that I end up with a similar look to your originals, or do I just have to experiment with that?

Some details in this comment:

cylc-doc/src/user-guide/interventions/index.rst

Lines 48 to 55 in 8afb75d

	.. NOTE - Creating screen recordings
	* Use the dimensions 650x720 for your recording area.
	* On my setup that works out as 72 cols by 40 rows in the terminal.
	* Keep it as short as possible without being disorientating.
	* Document top-level use cases, don't attempt to cover every
	possible intervention.
	* I've been installing workflows as "myworkflow".

Something I didn't mention there, but should have, is the terminal theme I used (Gnome - Tango Dark) for Tui recordings.

[oliver-sanders]

I get what you mean here (children = graph children), but I don't think users will.

We can omit this (there is no reason to think that this might happen):

Suggested change

	until released. The children of held tasks are not automatically held.
	until released.

[hjoliver]

Agreed on graph children.

Less agreed on "there's no reason to think..." - I've had it several times from users who tried to "hold everything" by holding "all the tasks" - which doesn't hold everything because the children of any active tasks will carry on.

However, I'll take your suggestion.

[oliver-sanders]

Could also do with a quick entry in the changes section, we'll post this on Discourse, etc to advertise the change in behavior.

[hjoliver]

Text review suggestions addressed.

TODO:

• example animation
• add to the changes section

[wxtim]

Fixes,

• Animation
• Including for spelling which is breaking the test

Does not add stuff to the changes section to avoid conflict.

hjoliver#3

[MetRonnie]

Superseded by #790