[Request]: Document private locations space awareness !!

[shahzad31]

Description

Since this PR elastic/kibana#202634

Private location can now be space aware, essentially user can either create location in all spaces, or multiple spaces or single space.
We need to document this feature in private location synthetics documents. When creating a location in flyout use can choose this via combobox. If user choose all spaces, in that case if they don't have permission to create resources in all space, it will throw an error.

Resources

elastic/kibana#202634

Which documentation set does this change impact?

Stateful and Serverless

Feature differences

It's same

What release is this request related to?

N/A

Collaboration model

The documentation team

Point of contact.

Main contact: @shahzad31

Stakeholders: