Issue #5626: Remove misleading comment from socket.gethostname() documentation

A machine can have more than one IP addresses so
socket.gethostbyname(socket.gethostname()) probably won't return the correct
one.

Doc/library/socket.rst

@@ -568,11 +568,6 @@ The :mod:`socket` module also offers various network-related services:
    Return a string containing the hostname of the machine where  the Python
    interpreter is currently executing.
 
-   If you want to know the current machine's IP address, you may want to use
-   ``gethostbyname(gethostname())``. This operation assumes that there is a
-   valid address-to-host mapping for the host, and the assumption does not
-   always hold.
-
    Note: :func:`gethostname` doesn't always return the fully qualified domain
    name; use :func:`getfqdn` for that.