add info about html comments to error form

src/main/java/org/cryptomator/ui/common/ErrorController.java

@@ -31,7 +31,9 @@ public class ErrorController implements FxController {
 			
 			<!-- ✏ Please describe what happened as accurately as possible. -->
 			
-			<!-- 📋 Please also copy and paste the detail text from the error window to the next line. -->
+			<!-- 📋 Please also copy and paste the detail text from the error window. -->
+			
+			<!-- ℹ Text enclosed like this (chevrons, exclamation mark, two dashes) is not visible to others! -->
 			
 			<!-- ❗ If the description or the detail text is missing, the discussion will be deleted. -->
 			""";