Use default: in arg descriptions too, standardising the format (#208)

Author: FollowTheProcess

command.go

@@ -579,7 +579,7 @@ func writeArgumentsSection(cmd *Command, s *strings.Builder) error {
 	for _, arg := range cmd.args {
 		line := fmt.Sprintf("  %s\t%s\t%s\t[required]", style.Bold.Text(arg.Name()), arg.Type(), arg.Usage())
 		if arg.Default() != "" {
-			line = fmt.Sprintf("  %s\t%s\t%s\t[default %s]", style.Bold.Text(arg.Name()), arg.Type(), arg.Usage(), arg.Default())
+			line = fmt.Sprintf("  %s\t%s\t%s\t[default: %s]", style.Bold.Text(arg.Name()), arg.Type(), arg.Usage(), arg.Default())
 		}
 
 		fmt.Fprintln(tw, line)

testdata/snapshots/TestHelp/with_named_arguments.snap.txt

@@ -5,8 +5,8 @@ Usage: test [OPTIONS] SRC [DEST] [OTHER]
 Arguments:
 
   src    string  The file to copy        [required]
-  dest   string  Destination to copy to  [default default.txt]
-  other  int     Something else          [default 0]
+  dest   string  Destination to copy to  [default: default.txt]
+  other  int     Something else          [default: 0]
 
 Options:
 

testdata/snapshots/TestHelp/with_verbosity_count.snap.txt

@@ -5,7 +5,7 @@ Usage: test [OPTIONS] SRC [DEST]
 Arguments:
 
   src   string  The file to copy        [required]
-  dest  string  Destination to copy to  [default destination.txt]
+  dest  string  Destination to copy to  [default: destination.txt]
 
 Options: