track usage via github search

[bgruening]

e.g. https://github.com/search?utf8=%E2%9C%93&q=biocontainers%2F&type=Code

[ypriverol]

@bgruening Thanks a lot for the issue. We will need to trace:

• [ ] General containers use by github code files: Would be nice to detect type of the file: bash script, workflow etc.
• [ ] We need to create some rules to eliminate everything that is our containers definition.