docs: add 'What We Are' heading, convert intro to normal text

[EricNGOntos]

Summary

Minor README formatting improvement for the product positioning section introduced in PR #71.

Changes

• Added ## What We Are heading: Gives the positioning block a proper section title for better navigation and visual hierarchy.
• Converted slogan and product description from blockquote to normal text: The bold slogan and the product definition paragraph were previously rendered as gray blockquotes. They are now standard white text for better readability and visual prominence.
• TIP callout preserved as-is: The detailed explanation about standing on open-source parsers remains in the green TIP box.

Documentation-only change. No code modifications.