Prevent corruption of "Icon\r" rule

https://stackoverflow.com/questions/17556250/how-to-ignore-icon-in-git/33974028#33974028

https://github.com/github/gitignore/pulls?q=is%3Apr+Icon+%5Cr

Global/macOS.gitignore

@@ -3,8 +3,9 @@
 .AppleDouble
 .LSOverride
 
-# Icon must end with two \r
-Icon␍
+# Start of Icon[\r] pattern
+Icon[␍]
+# End of Icon[\r] pattern
 
 # Thumbnails
 ._*