[erlang-bugs] System messages documentation

[Dmitriy Kargapolov]

I'm not sure about whole chapter describing module sys, but at least 
format of get_modules message and its expected reply should be fixed.
The document said: "This message is {get_modules, From}. The reply to 
this message is From ! {modules, Modules}, where Modules is a list of 
the currently active modules in the process."
But actually message pattern is: {Label, {From, MRef}, get_modules}, and 
response should be in form {MRef, Modules}, where Label in current 
implementation seems to be equal to From, and MRef is reference (used 
internally, returned by erlang:monitor/2).