Adding initial debugging instructions for starlingmonkey debugger extension

[squillace]

This is a first commit describing how to use the StarlingMonkey debugger extension as it currently exists. It, like the debugger, remains a work in progress.

[squillace]

@tschneidereit @andreiltd Have a look.

[andreiltd]

Did I really? 🤔 Probably a missclick, sorry for the noise.