Improve docs around pipeline target types

[Steve-Mcl]

closes #3316

Description

• List out the "Target Types" for a pipeline stage
• List out the "Actions" for a pipeline stage
• Additional info around device groups
• Add feature availability for device groups

Related Issue(s)

#3316

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production

Labels

• Backport needed? -> add the backport label
• Includes a DB migration? -> add the area:migration label

[ZJvandeWeg]

@joepavitt can you assist from a user perspective? And we both do a pass?

[Steve-Mcl]

@ZJvandeWeg @joepavitt I beleive I have addressed your many many many comments (yikes - didnt realise I was sooooo bad at docs!)

Can you both give it one last look over please so we can get it merged and I can pull/merge and finish up the PR on branch 3260-update-device-on-group-membership-change

[Steve-Mcl]

Final tweaks complete.

[ZJvandeWeg]

Thanks for the additional screenshots!

[Steve-Mcl]

@ZJvandeWeg

final wording around requirements is now:

The following requirements apply:

• FlowFuse 1.15+ Enterprise Tier
• FlowFuse Cloud teams on the Enterprise tier

Does this read how you expect/hope 🤞

EDIT:

Does this mean we should update other docs:

• https://github.com/FlowFuse/flowfuse/blob/main/docs/user/high-availability.md#L12
• https://github.com/FlowFuse/flowfuse/blob/main/docs/contribute/introduction.md#L176-L179
• https://github.com/FlowFuse/flowfuse/blob/main/docs/admin/sso/README.md#L7-L8

[joepavitt]

Just pushed some formatting changes, the stage actions being H4's made the article difficult to read, so changed them to boldened bullets instead.