pushing branch with -f is dangerous

CONTRIBUTING.org

@@ -35,10 +35,8 @@
    Apply your modifications in that "Feature" branch. Then, you need
    to push this branch on your online repository
    #+begin_src sh
-   git push -f origin your_branch_name
+   git push origin your_branch_name
    #+end_src
-   or without -f, if the branch already exists online, and you just
-   want to update it.
 
 ** Merge request
    Once your branch is online, on the gitlab interface, go to the