clarified that select() timeouts should always remain rather short

docs/libcurl/curl_multi_fdset.3

 .\" $Id$
 .\"
-.TH curl_multi_fdset 3 "3 May 2002" "libcurl 7.9.5" "libcurl Manual"
+.TH curl_multi_fdset 3 "15 Apr 2004" "libcurl 7.9.5" "libcurl Manual"
 .SH NAME
 curl_multi_fdset - extracts file descriptor information from a multi handle
 .SH SYNOPSIS
@@ -22,6 +22,12 @@ of them are ready to be read from or written to.
 NOTE that once this call is made, you must not remove the sets you point to,
 as libcurl will need to be able to read them. It needs them after select()
 calls, to know if certain sockets are readable or writable.
+
+You should also be aware that when doing select(), you should consider using a
+rather small (single-digit number of seconds) timeout and call
+\fIcurl_multi_perform\fP regularly - even if no activity has been seen on the
+fd_sets - as otherwise libcurl-internal retries and timeouts may not work as
+you'd think.
 .SH RETURN VALUE
 CURLMcode type, general libcurl multi interface error code. See
 \fIlibcurl-errors(3)\fP