Patch #1015012. Improve markup and punctuation in libsocket.tex
diff --git a/Doc/lib/libsocket.tex b/Doc/lib/libsocket.tex
index 762d762..db0b767 100644
--- a/Doc/lib/libsocket.tex
+++ b/Doc/lib/libsocket.tex
@@ -305,10 +305,10 @@
\begin{funcdesc}{socketpair}{\optional{family\optional{, type\optional{, proto}}}}
Build a pair of connected socket objects using the given address
-family, socket type and protocol number. Address family, socket type
+family, socket type, and protocol number. Address family, socket type,
and protocol number are as for the \function{socket()} function above.
-The default family is AF_UNIX if defined for the platform, otherwise
-the default is AF_INET.
+The default family is \constant{AF_UNIX} if defined on the platform;
+otherwise, the default is \constant{AF_INET}.
Availability: \UNIX. \versionadded{2.4}
\end{funcdesc}