[8.14] [BUG][ESS][8.13-8.14] Add that suppression is supported for indicator match rules and other cleanup (backport #5116)

[mergify]

Contributes to #5115

Previews:

• Create custom query rule - Removed duplicate content in step 3 since we already point users towards the more detailed suppression docs.
• Create a threshold rule - Same as above.
• Create an indicator match rule - Added that suppression can be configured on the rule (see step 3).

Twin Serverless PR: https://github.com/elastic/staging-serverless-security-docs/pull/331

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This is an automatic backport of pull request #5116 done by [Mergify](https://mergify.com).

[github-actions]

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