Added information about memory sizes to man page

The man page now contains the section "MEMORY SIZES" which talks about
the convention used for representing memory sizes and why it was chosen.

htop.1.in

@@ -353,6 +353,15 @@ You may override the location of the configuration file using the $HTOPRC
 environment variable (so you can have multiple configurations for different
 machines that share the same home directory, for example).
 
+.SH "MEMORY SIZES"
+.LP
+Memory sizes in htop are displayed as they are in tools from the GNU Coreutils
+(when ran with the --human-readable option). This means that sizes are printed
+in powers of 1024. (e.g., 1023M = 1072693248 Bytes)
+.LP
+The decision to use this convention was made in order to conserve screen space
+and make memory size representations consistent throughout htop.
+
 .SH "SEE ALSO"
 proc(5), top(1), free(1), ps(1), uptime(1)