Update CONTRIBUTING.md

Author: tuvtran

CONTRIBUTING.md

@@ -11,11 +11,11 @@ Before making a pull request, please make sure of the following:
 * If your tutorial is a multi-part series, use the following format:
     ```
         * Title
-            * [Part 1](!link_to_part_1)
-            * [Part 2](!link_to_part_2)
+            * [Part 1](link_to_part_1)
+            * [Part 2](link_to_part_2)
     ```
 * Check the spelling and grammar
 * Remove any trailing whitespaces
 * Links must be pointing straight to the tutorials, no URL shorteners. However, if the URL is too long (more than 80 characters), Google URL Shortener is allowed
 
-Thank you for your suggestions! If you think there is anything to improve with the guidelines, please contact me at <[email protected]>
+Thank you for your suggestions! If you think there is anything to improve with the guidelines, please contact me at <[email protected]>