Multiple fixes to 'docker stats' output:

* Add space between values in docker stats output for easier parsing

  Old output could not be parsed easily because there were columns
  that did not have any separator. Also values that are together
  without any space is difficult to read even for humans.

* Update unit.HumanSize comment to match what the does actually does

Signed-off-by: Otto Kekäläinen <otto@seravo.fi>

man/docker-stats.1.md

@@ -28,4 +28,3 @@ Run **docker stats** with multiple containers.
     CONTAINER           CPU %               MEM USAGE / LIMIT     MEM %               NET I/O
     redis1              0.07%               796 KB / 64 MB        1.21%               788 B / 648 B
     redis2              0.07%               2.746 MB / 64 MB      4.29%               1.266 KB / 648 B
-

pkg/units/size.go

@@ -49,7 +49,7 @@ func CustomSize(format string, size float64, base float64, _map []string) string
 }
 
 // HumanSize returns a human-readable approximation of a size
-// using SI standard (eg. "44kB", "17MB").
+// capped at 4 valid numbers (eg. "2.746 MB", "796 KB").
 func HumanSize(size float64) string {
 	return CustomSize("%.4g %s", size, 1000.0, decimapAbbrs)
 }