docs: improve presentation of browser

[firecrawl-spring]

Page: https://docs.firecrawl.dev/features/browser

Summary of presentation changes

• Tightened opening description: Condensed to a single lead sentence followed by a scannable bullet list of key capabilities, matching the reference page pattern
• Added intro sentences to code sections: "Launch a session" and "Execute code" sections now have brief context before jumping into code blocks
• Restructured headings: Promoted "Persistent sessions" to a top-level section (it was the primary subsection under "Session management"), keeping "Session management" for list/TTL/close operations. Renamed "agent-browser (Bash Mode)" to just "agent-browser" and "CLI" to "CLI execute" for clarity
• Standardized heading case: Changed all headings to sentence case (e.g., "Quick Start" to "Quick start", "Live View" to "Live view")
• Combined "When to Use Browser" and "Use Cases": Merged into a single section with the comparison table followed by example use cases as a subsection
• Combined "Pricing" and "Rate limits": Merged into a single "Pricing and limits" section using a table
• Removed dashes in prose: Replaced em-dashes with commas, colons, or restructured sentences throughout
• Improved table formatting: Replaced — in the profile parameter table with (required) for clarity
• Added context to "Close a session": Added a brief sentence explaining what closing does (frees resources, saves persistent profile state)
• Added context to "List sessions": Added an intro sentence before the code block

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 2 additional findings.