Update docs formatting & indentation

[sun-mir]

Description

⚠️ Only *.mdx related documentation changes

Background

The existing plugin documentation page is badly formatted and hard to use. My MR attempts to fix some of the problems and use the observed best practices from other pages

Existing ToC

Changes

• standardized H2 vs H3 (vs H4) headers
• changed H3 titles for repeatable Optional (fields) sections to bold styling
• wrapped HCL2/JSON code snippets into switchable table divs
• deleted duplicated paragraph for Communicator Configuration
• moved section about SSH key pair automation under the original Communicator Configuration paragraph

Resolved Issues

No tracked issues exist

Rollback Plan

Unlikely applicable since PR brings no functional source code changes...

Changes to Security Controls

N/a

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