[DOC] Format all API pages according to the API template

[samipak458]

Description

Fix API reference section according to API template.

• Reordering the sections so that they are in the correct order.
• Ensuring all field names and variables are in code font (surrounded by tick marks (`)).
• Ensuring the headings are heading level 2 for the section names and level 4 for examples.
• Make heading levels consistent across pages.
• Make sure API names use the same capitalization.
• Make sure that each page uses terminology that matches the template.

Issues Resolved

Closes Issue opensearch-project#4689

Checklist

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