Added --staged as an alternative

README.md

@@ -158,7 +158,7 @@ git diff
 
 ## Changes staged for commit
 ```sh
-git diff --cached or git diff --staged
+git diff --cached
 ```
 
 ## Show both staged and unstaged changes

tips.json

@@ -24,7 +24,8 @@
     "tip": "git diff"
 }, {
     "title": "Changes staged for commit",
-    "tip": "git diff --cached or git diff --staged"
+    "tip": "git diff --cached",
+    "alternatives": "git diff --staged"
 }, {
     "title": "Show both staged and unstaged changes",
     "tip": "git diff HEAD"