fix(workflows): add example with latest version of Nginx

[assiaait]

This PR adds GitHub Actions workflows for building and testing the latest Nginx example:

• .github/workflows/example-nginx-stable.yaml
• .github/workflows/example-nginx-staging.yaml

The workflows build the Nginx example using KraftKit and verify it with a curl request to localhost:8080.

[assiaait]

Hi @razvand,

This is a draft PR for adding Nginx example workflows.

Please review and give feedback.

Direct commit link: 67e9c8d
Full PR link: #219

[razvand]

Why are updates to the index.html and app-nginx?

For the actual workflow files, copy and adapt from existing workflow files, no need to start from scratch.

[razvand]

Why change the runtime?

[assiaait]

Hi @razvand,

Thanks for the review and the feedback! I understand the confusion regarding the extra changes. My goal was to update the example to ensure it uses the most robust and maintainable approach for the latest Nginx version.

[razvand]

You have an nginx-1.25/app-nginx` symbolic link or something weird. Remove it.

Use only two commit messages: one for moving the current nginx/ directory to nginx-1.25/ and another for adding the current nginx-1.27/ directory.

The .github/workflow/ directory is in the root directory of the repository, not a subdirectory of an example.

Write good commit messages. See the commit history, and use similar messages. Sign-off your commits.

[nurof3n]

Pls update the version of the existing nginx example instead