Fix help text for generic flag to not insinuate that you can specify multiple

Feels like it may have been copied from StringSliceFlag or something,
but update the output to be more consistent with other single value
flags.

Also added comments to the String and Apply functions.

flag.go

@@ -67,10 +67,15 @@ type GenericFlag struct {
 	EnvVar string
 }
 
+// String returns the string representation of the generic flag to display the
+// help text to the user (uses the String() method of the generic flag to show
+// the value)
 func (f GenericFlag) String() string {
-	return withEnvHint(f.EnvVar, fmt.Sprintf("%s%s %v\t`%v` %s", prefixFor(f.Name), f.Name, f.Value, "-"+f.Name+" option -"+f.Name+" option", f.Usage))
+	return withEnvHint(f.EnvVar, fmt.Sprintf("%s%s '%v'\t%v", prefixFor(f.Name), f.Name, f.Value, f.Usage))
 }
 
+// Apply takes the flagset and calls Set on the generic flag with the value
+// provided by the user for parsing by the flag
 func (f GenericFlag) Apply(set *flag.FlagSet) {
 	val := f.Value
 	if f.EnvVar != "" {

flag_test.go

@@ -262,15 +262,14 @@ var genericFlagTests = []struct {
 	value    cli.Generic
 	expected string
 }{
-	{"help", &Parser{}, "--help <nil>\t`-help option -help option` "},
-	{"h", &Parser{}, "-h <nil>\t`-h option -h option` "},
-	{"test", &Parser{}, "--test <nil>\t`-test option -test option` "},
+	{"test", &Parser{"abc", "def"}, "--test 'abc,def'\ttest flag"},
+	{"t", &Parser{"abc", "def"}, "-t 'abc,def'\ttest flag"},
 }
 
 func TestGenericFlagHelpOutput(t *testing.T) {
 
 	for _, test := range genericFlagTests {
-		flag := cli.GenericFlag{Name: test.name}
+		flag := cli.GenericFlag{Name: test.name, Value: test.value, Usage: "test flag"}
 		output := flag.String()
 
 		if output != test.expected {