Manual pages fixes

Taken from Debian with small changes added

Authors: Craig Small <csmall@debian.org>, Brendan O'Dea <bod@debian.org>

uptime.1

@@ -6,7 +6,8 @@ uptime \- Tell how long the system has been running.
 .SH SYNOPSIS
 .B uptime
 .br
-.BR uptime " [" "\-V" ]
+.B uptime
+.RB [ \-V ]
 .SH DESCRIPTION
 .B uptime
 gives a one line display of the following information.
@@ -14,13 +15,25 @@ The current time,
 how long the system has been running,
 how many users are currently logged on,
 and the system load averages for the past 1, 5, and 15 minutes.
-.sp
+
 This is the same information contained in the header line displayed by 
 .BR w (1).
+.sp
+System load averages is the average number of processes that are either
+in a runnable or uninterruptable state.  A process in a runnable state is
+either using the CPU or waiting to use the CPU. A process in
+uninterruptable state is waiting for some I/O access, eg waiting for
+disk.  The averages are taken over the three time intervals.
+Load averages are not normalized for the number of CPUs in a system, so
+a load average of 1 means a single CPU system is loaded all the time
+while on a 4 CPU system it means it was idle 75% of the time.
 .SH FILES
-.IR /var/run/utmp "	information about who is currently logged on"
-.br
-.IR /proc "	process information"
+.TP
+.I /var/run/utmp
+information about who is currently logged on
+.TP
+.I /proc
+process information
 .SH AUTHORS
 .B uptime
 was written by Larry Greenfield <greenfie@gauss.rutgers.edu> and