Enhance AI Model Configuration and Authentication

[hyperlint-ai]

This pull request updates the documentation to comply with the style guide by addressing various formatting and clarity issues. Key changes include the use of standard quotes, removal of contractions, and ensuring proper heading punctuation. Additionally, links have been updated to use relative paths instead of full URLs.

• Updated the configuration description for clarity and compliance with the style guide (using-ai-models.mdx)
• Changed a link to use a relative path instead of a full URL (testing-your-agent.mdx)
• Revised sentences for clarity and removed contractions in the authentication section (remote-mcp-server.mdx)
• Adjusted wording for clarity and compliance in the local proxy section (test-remote-mcp-server.mdx)
• Fixed punctuation and clarity issues in the index file (index.mdx)