better help

README.md

@@ -9,13 +9,19 @@ like `lookup`.
 
 ```bash
 $ ./spry
-Usage of ./spry:
+Usage of ./spry [Options] [Template Files]:
   -d string
         Output delimiter between template files rendered (default "---")
   -f value
         Specify a values file (JSON or YAML)
   -helm
-        Whether to nest provided values under .Values
+        Helm compatibility: provided values will be nested under .Values
   -set value
         Set a specific value (foo.bar=spam)
+
+Template Files can also be directories to recurse for templates.
+
+If no template files are provided it will attempt read from STDIN.
+If no input is available from STDIN it will print this usage message instead.
+Pass only '-' to Template Files to force waiting for input.
 ```

main.go

@@ -88,8 +88,36 @@ func init() {
 		"d", "---",
 		"Output delimiter between template files rendered",
 	)
-	flag.BoolVar(&flags.helmCompat, "helm", false, "Whether to nest provided values under .Values")
+	flag.BoolVar(
+		&flags.helmCompat,
+		"helm", false,
+		"Helm compatibility: provided values will be nested under .Values",
+	)
 	flag.Parse()
+
+	flag.Usage = func() {
+		fmt.Fprintf(flag.CommandLine.Output(), "Usage of %s [Options] [Template Files]:\n", os.Args[0])
+		flag.PrintDefaults()
+		fmt.Fprintf(flag.CommandLine.Output(), "\n")
+		fmt.Fprintf(
+			flag.CommandLine.Output(),
+			"Template Files can also be directories to recurse for templates.\n",
+		)
+		fmt.Fprintf(flag.CommandLine.Output(), "\n")
+		fmt.Fprintf(
+			flag.CommandLine.Output(),
+			"If no template files are provided it will attempt read from STDIN.\n",
+		)
+		fmt.Fprintf(
+			flag.CommandLine.Output(),
+			"If no input is available from STDIN it will print this usage message instead.\n",
+		)
+		fmt.Fprintf(
+			flag.CommandLine.Output(),
+			"Pass only '-' to Template Files to force waiting for input.\n",
+		)
+		fmt.Fprintf(flag.CommandLine.Output(), "\n")
+	}
 }
 
 func checkErr(err error) {