Document debouncePeriod

[staltz]

This is an internal config, exposed in the ssb config object just to make it easier for tests, so we don't need a README documentation, but if you want, you can add some code comments. It basically controls how often will we trigger ssb.ebt.request() calls. We trigger those when the requestManager.add() has "calmed down", i.e. after debouncePeriod milliseconds have passed in which add() was not called.

[staltz]

A timeline of what debounce looks like, assuming 100ms of debouncePeriod:

                   |---100ms---|
-----o-----o---o---o----------------->

-------------------------------o----->

[Powersource]

documented in 8abaeee4311a74b6592e25171854a9f15e77483d now