Merge pull request #1 from syohex/syohex/typo

Fix typo

Author: jcs090218

README.md

@@ -9,7 +9,7 @@
 Call the following command to enable it.
 
 ```
-M-x ivy-file-preivew-mode
+M-x ivy-file-preview-mode
 ```
 
 ## Contribution