title: How to commit new changes to an open merge request?
body: <p>I am new to working in branching and git.</p>
  <p>I developed some test cases and created new branch to push the changes in that branch and opened a merge request in GitLab to be merged in master branch.</p>
  <p>After PR, my reviewer highlighted some code refactoring and other minor changes.</p>
  <p>Now, I have made those changes and the merge request is still open.  How can I push the new changes/commit to an already opened merge request?</p>