Ghostwriter: fix supported filetypes

Ghostwriter is a text editor, it doesn't open images...
Improved summary and description.

app-text/ghostwriter/additional-files/ghostwriter.rdef.in

@@ -5,18 +5,18 @@ resource app_version {
 	major  = @MAJOR@,
 	middle = @MIDDLE@,
 	minor  = @MINOR@,
-	
+
 	variety = B_APPV_FINAL,
 	internal = 0,
-	
-	short_info = "ghostwriter",
+
+	short_info = "Ghostwriter",
 	long_info = "@LONG_INFO@"
 };
 
 resource app_signature "@APP_SIGNATURE@";
 
 resource file_types message {
-	"types" = "image"
+	"types" = "text"
 };
 
 resource vector_icon {