Docstring for backlog parameter of listenTCP should describe its effects

[oberstet]

The docstring for the backlog parameter of listenTCP/listenSSL could be improved:

"Size of the listen queue. The value is passed directly to the listen system call and it's precise semantics is defined by the platform Twisted runs on."

This way users are made aware that it's not a Twisted-internal tunable, but forwarded to OS, and the effects being platform dependent.

[rwall]

It should be easy to add oberstets suggested docstring improvement to the appropriate interfaces:

•  https://twistedmatrix.com/documents/current/api/twisted.internet.interfaces.IReactorTCP.html#listenTCP
• source:trunk/twisted/internet/interfaces.py#L620
•  https://twistedmatrix.com/documents/current/api/twisted.internet.interfaces.IReactorSSL.html#listenSSL
• source:trunk/twisted/internet/interfaces.py#L688

[exarkun]

Size of the listen queue. The value is passed directly to the listen system call and it's precise semantics is defined by the platform Twisted runs on.

The second part of this is definitely true. I'm not sure the first part is. Popular platforms seem to largely ignore this value entirely.