Better parsing error for scope and template

Signed-off-by: jolheiser <john.olheiser@gmail.com>

scope.go

@@ -1,7 +1,7 @@
 package spectre
 
 import (
-	"errors"
+	"fmt"
 	"strings"
 )
 
@@ -41,7 +41,7 @@ func ParseScope(s string) (Scope, error) {
 	case "recovery", "r":
 		return Recovery, nil
 	default:
-		return "", errors.New("unknown Scope")
+		return "", fmt.Errorf("unknown Scope %q; available [authentication, identification, recovery]", s)
 	}
 }
 

template.go

@@ -1,7 +1,7 @@
 package spectre
 
 import (
-	"errors"
+	"fmt"
 	"strings"
 )
 
@@ -39,7 +39,7 @@ func ParseTemplate(s string) (Template, error) {
 	case "basic":
 		return Basic, nil
 	default:
-		return "", errors.New("unknown Template")
+		return "", fmt.Errorf("unknown Template %q; available [maximum, long, medium, short, pin, name, phrase, basic]", s)
 	}
 }