Removes Stoplight API docu auto build orb.

[wintermeyer]

Stoplight changed its system to build the API documentation.

We can't trigger the build as we used to but on the bright side circleci can now watch the GitHub repository and triggers the build by itself. That is already configured (kudos to @kennyadsl). This PR removes the old .circleci/config.yaml configuration for the stoplight/push and stoplight/build.

Warning: I did run circleci config validate but other than that I had no way to test this.

To-Do

• Remove $STOPLIGHT_GIT_TOKEN and $STOPLIGHT_API_TOKEN as env variables in the CI.

Checklist:

• I have followed Pull Request guidelines
• I have added a detailed description into each commit message
• I have updated Guides and README accordingly to this change (if needed)
• I have added tests to cover this change (if needed)
• I have attached screenshots to this PR for visual changes (if needed)

[kennyadsl]

Thanks, Stefan!

[kennyadsl]

I backported this change in v2.11, v3.0 and v3.1 to avoid trying to sync when we make changes to those branches.

On a side note, this sync is still enabled (for 3.0 and 3.1 branches) and configured directly in Stoplight. It will listen via webhooks to any change in these branches and update the REST API documentation for that specific version accordingly.

Users will be able to choose the right version with the dedicated menu:

.

The last released version will be the default.