@niconbw Can you tell how to add this username to README.md at the end in append mode ? I am new with actions.

Hi @theSwapnilSaste
Please try to use git command to update README.md. Such as:

name: Add to Contributors
on:
  pull_request:
    branches:
    - master
jobs:

comment:

runs-on: ubuntu-latest

steps:

- uses: actions/checkout@master
- name: Modify README.md
  run: |
    echo '<br> Adding this ${{ github.event.pull_request.user.login }} to Contributors' >> README.md
    
- name: Commit files
  run: |
      git config --local user.email "test@github.com"
      git config --local user.name "GitHub Action test"
      git add ./README.md
      git commit -m "Add Contributors"
- name: Push changes # push the README.md to your repo
  uses: ad-m/github-push-action@master
  with:
    branch: master #ignore if your branch is master
    github_token: ${{ secrets.GITHUB_TOKEN }}
    force: true

Hi @theSwapnilSaste
Did the git command meet your needs? Feel free to contact me if there is any questions related to this ticket.