Generated Markdown files should have comment that describes which script generated it

[gkossakowski]

Given the fact that we generate those files in this project and then use it somewhere else (e.g. in scala-lang) it would be good to include a comment in generated Markdown file that points back at script that generated it.

It would vastly help to understand where given files are coming from when analyzing history of previous releases.

[adriaanm]

ironically, markdown breaks on comments: scala/scala-lang#158