[myhdl-list] Typo in docs

[Henry G. <he...@ca...>]

There is a typo in the docs for ResetSignal 
http://docs.myhdl.org/en/latest/manual/reference.html#myhdl.ResetSignal

As it reads, both True and False async args lead to an asynchronous reset.

I've pushed this (minor) change to my fork and can raise a PR if desired.

Cheers,

Henry