[6.1] 816753906 Document the 'changed' parameter for param.show.

[hermunn]

commit 816753906c1118991e8993f1db3acc76b6ee1ba0
Author: Geoff Simmons <geoff at uplex.de>
Date:   Tue Sep 25 10:10:39 2018 +0200

    Document the 'changed' parameter for param.show.

diff --git a/include/tbl/cli_cmds.h b/include/tbl/cli_cmds.h
index d162bada5..7b3d1de19 100644
--- a/include/tbl/cli_cmds.h
+++ b/include/tbl/cli_cmds.h
@@ -134,9 +134,14 @@ CLI_CMD(VCL_LABEL,
 
 CLI_CMD(PARAM_SHOW,
 	"param.show",
-	"param.show [-l] [<param>]",
+	"param.show [-l] [<param>|changed]",
 	"Show parameters and their values.",
-	"",
+
+	"The long form with ``-l`` shows additional information, including"
+	" documentation and minimum, maximum and default values, if defined"
+	" for the parameter. If a parameter is specified with ``<param>``,"
+	" show only that parameter. If ``changed`` is specified, show only"
+	" those parameters whose values differ from their defaults.",
 	0, 2
 )