Update README.md

typo fixing

Author: arsdever

README.md

@@ -62,5 +62,5 @@ _A list of my commonly used Git commands_
 | ------- | ----------- |
 | `git log` | View changes |
 | `git log --summary` | View changes (detailed) |
-| `git diff [source branch] [target branch}` | Preview changes before merging |
+| `git diff [source branch] [target branch]` | Preview changes before merging |