Documentation: proc.rst: add more about the 6 fields in loadavg

Address Jon's feedback on the previous patch by adding info about
field separators in the /proc/loadavg file.

Signed-off-by: Randy Dunlap <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/filesystems/proc.rst

···
                 number of processes currently runnable (running or on ready queue);
                 total number of processes in system;
                 last pid created.
+                All fields are separated by one space except "number of
+                processes currently runnable" and "total number of processes
+                in system", which are separated by a slash ('/'). Example:
+                  0.61 0.61 0.55 3/828 22084
  locks        Kernel locks
  meminfo      Memory info
  misc         Miscellaneous