[Man] Update man page on xrdfs prepare

docs/man/xrdfs.1

@@ -113,6 +113,21 @@ Remove a directory.
 .RS 3
 Truncate a file.
 
+.RE
+\fBprepare\fR \fI[-c]\fR \fI[-f]\fR \fI[-s]\fR \fI[-w]\fR \fI[-p priority]\fR \fIfilenames\fR
+.RS 3
+Prepare one or more files for access.
+.br
+\fI-c\fR co-locate staged files if possible
+.br
+\fI-f\fR refresh file access time even if the location is known
+.br
+\fI-s\fR stage the files to disk if they are not online
+.br
+\fI-w\fR whe files will be accessed for modification
+.br
+\fI-p\fR priority of the request, 0 (lowest) - 3 (highest)
+
 .SH NOTES
 For the list of available environment variables please refere to xrdcopy(1)