Feat: developer onboarding notification added

[Mayank77maruti]

Addess issue #1043

📑 Description
This PR introduces a new GitHub Action that automatically posts a comment on a pull request once it has been merged into the main branch.

[Mayank77maruti]

Hey @doberst , could you please review the pr.
I am participating in a opensource competition and it would be really great if you could review this pr.

[doberst]

@Mayank77maruti - really appreciate your contribution ... unfortunately, we tend to not use a lot of custom github actions in our development process or community engagement. Do you see another way perhaps to achieve this goal without layering in another github action?

[Mayank77maruti]

Thank you for your feedback on the GitHub Action!
I can use GitHub Webhook paired with a serverless function (hosted on platforms like AWS Lambda, Vercel, or Netlify). Here’s how it would work:

Webhook Setup: I’d set up a webhook on the repository that listens for the pull_request event (specifically for merged PRs).You can set this up in the Settings of your GitHub repository under Webhooks.

Serverless Function: When the webhook is triggered, it would call a serverless function. This function would:
Fetch the author's previous contributions to determine the number of merged PRs.
Post a congratulatory message on the pull request, with wording that dynamically changes based on the author’s contribution count.

GitHub API: The function would use the GitHub API with a Personal Access Token (PAT) to comment directly on the PR, without adding any custom GitHub Action files to the repo.