docs: add documentation descriptions to globalConfig's schema file

[soleksy-splunk]

Issue number: ADDON-70521

Summary

Adding documentation descriptions to json schema file.

Changes

Added description for all of fields in json schema file.

User experience

Currently user should be much more comfortable t use just json schema, and do not need to open documentation in second tab to check everything.

Checklist

If your change doesn't seem to apply, please leave them unchecked.

• I have performed a self-review of this change
• Changes have been tested
• Changes are documented
• PR title follows conventional commit semantics

[artemrys]

@hetangmodi-crest please review the changes related to the Alerts

[vtsvetkov-splunk]

Can we somehow increase visibility of the playground feature? The problem I see that we have to explain where to find it

And even if I open it, I don't see the killer feature right away

I have to notice that there is a tab JSON Schema where the whole editor is hidden.

Is there any way to add some documentation for stories?
Like here

[soleksy-splunk]

regarding Viktor comment as discussed it will be made with separate ticket and PR