[DOC] Update detection rule creation UI documentation in Security Analytics

[amsiglan]

What do you want to do?

• Request a change to existing documentation
• Add new documentation
• Report a technical problem with the documentation
• Other

Tell us about your request. Provide a summary of the request and all versions that are affected.
Detection rule creation UX is being simplified for 2.9 and we would like to update the page describing the details.
As part of simplification two changes have been made

1. A visual editor is provided for adding the detection section of the rule.
2. The sections have been rearranged to make rule creation more intuitive

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.
The new UX screenshots:

[cwillum]

Acknowledged. Will start this for 2.9 once I have an environment for screenshots (which play a large part of the updates).