Better document recovery alert behavior and incident management settings

What does this MR do?

• Related issues: #299962 (closed)
• Related MR: !57302 (merged)

Changes:

• Added documentation on alert and incident operations settings.
• Provided uniform documentation on recovery alerts for both HTTP Integrations and Prometheus Integrations.
• Added umbrella documentation on auto-closing alerts.

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because this is a docs-only MR.
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done