Add -H|--human flag to docker history

Add a flag to print sizes and dates in human readable format.

Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>

docs/man/docker-history.1.md

@@ -19,6 +19,9 @@ Show the history of when and how an image was created.
 **--help**
   Print usage statement
 
+**-H**. **--human**=*true*|*false*
+    Print sizes and dates in human readable format. The default is *true*.
+
 **--no-trunc**=*true*|*false*
    Don't truncate output. The default is *false*.
 

docs/sources/reference/commandline/cli.md

@@ -1191,6 +1191,7 @@ This will create a new Bash session in the container `ubuntu_bash`.
 
     Show the history of an image
 
+      -H, --human=true     Print sizes and dates in human readable format
       --no-trunc=false     Don't truncate output
       -q, --quiet=false    Only show numeric IDs