DOC: add manpage references to all system calls

Add a man section to every system call reference, giving users pointers to the
respective manpages.

Signed-off-by: Apollon Oikonomopoulos <apoikos@gmail.com>
diff --git a/doc/haproxy.1 b/doc/haproxy.1
index d58e2c7..6296767 100644
--- a/doc/haproxy.1
+++ b/doc/haproxy.1
@@ -110,25 +110,25 @@
 
 .TP
 \fB\-dk\fP
-Disable use of kqueue(). kqueue() is available only on BSD systems.
+Disable use of \fBkqueue\fP(2). \fBkqueue\fP(2) is available only on BSD systems.
 
 .TP
 \fB\-ds\fP
-Disable use of speculative epoll(). epoll() is available only on Linux 2.6
-and some custom Linux 2.4 systems.
+Disable use of speculative \fBepoll\fP(7). \fBepoll\fP(7) is available only on
+Linux 2.6 and some custom Linux 2.4 systems.
 
 .TP
 \fB\-de\fP
-Disable use of epoll(). epoll() is available only on Linux 2.6
+Disable use of \fBepoll\fP(7). \fBepoll\fP(7) is available only on Linux 2.6
 and some custom Linux 2.4 systems.
 
 .TP
 \fB\-dp\fP
-Disables use of poll(). select() might be used instead.
+Disables use of \fBpoll\fP(2). \fBselect\fP(2) might be used instead.
 
 .TP
 \fB\-dS\fP
-Disables use of splice(), which is broken on older kernels.
+Disables use of \fBsplice\fP(2), which is broken on older kernels.
 
 .TP
 \fB\-db\fP