docs: Add ffmpeg to roll_browser.js usage output (#5643)
docs: Add ffmpeg to roll_browser.js usage output (#5643)

This is a small change to show that ffmpeg is a supported browser parameter
value in the script usage. Although, the whole file should probably be
refactored now to something more generic like roll_download.js since ffmpeg
is just reusing the logic and isn't a browser.
microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright