History of WebSocket

Editorial review completed.

I found the section on buffered amount confusing. The way it was written, it implied that the buffered amount was always climbing.

Fixed page formatting to allow the compat data scraper to parse the page

Added table to 'Specifications' section and fixed page formatting to allow the compat data scraper to parse the page

Added constructor info from the page about writing WebSocket client apps

Replaced Gecko_callout_header macro with a simple note