fix: change sender field for CodeScanningAlert event to match other payloads

[wolfy1339]

Why:

In octokit/webhooks#371, a GitHub staffer sent us a PR with some new payload examples for the CodeScanningAlert event, the sender field was set to the value of the Github user (roughly the values of the REST endpoint GET /users/github) and not the GitHub org (the values of the REST endpoint GET /orgs/github)

All the other webhooks use the values that resemble the GET /users/{user} enpoint.

What's being changed:

Updates the sender field for the CodeScanningAlert event to reflect my findings, and to match the other webhook payloads

Check off the following:

• I have reviewed my changes in staging. (look for the deploy-to-heroku link in your pull request, then click View deployment)
• For content changes, I have reviewed the localization checklist
• For content changes, I have reviewed the Content style guide for GitHub Docs.

[welcome]

Thanks for opening this pull request! A GitHub docs team member should be by to give feedback soon. In the meantime, please check out the contributing guidelines.

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
translations/**
lib/rest/static/**
.github/workflows/**
.github/CODEOWNERS
translations/**
assets/fonts/**
data/graphql/**
lib/graphql/**
lib/redirects/**
lib/rest/**
lib/webhooks/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

[shati-patel]

Hi @wolfy1339, thank you for the pull request 😃

I've checked with our code scanning team and your updated example looks good. If you'd like to reopen this pull request, we'd love to take the contribution! Otherwise, we can make the change internally.

Thanks again for helping us improve our docs 🎉

[wolfy1339]

I reopened the pull request

[wolfy1339]

Fixes #3906

[shati-patel]

Thank you! I'll get this merged shortly.

Overridden manually

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
translations/**
lib/rest/static/**
.github/workflows/**
.github/CODEOWNERS
translations/**
assets/fonts/**
data/graphql/**
lib/graphql/**
lib/redirects/**
lib/rest/**
lib/webhooks/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

overridden manually