Add examples and documentation for implementing new matchers and metrics

[msschwartz21]

We had this listed in our project board from a while ago. Is this something that we would want to prioritize for the version 1 milestone?

[cmalinmayor]

Yes I think so! I'm adding it to the v1.0 milestone

[cmalinmayor]

In the future, we want developers of new metrics to also add:

• benchmarking
• page in documentation for their metrics
• tests with a variety of graphs (that we provide)

We should note this in the developer documentation, and perhaps in a PR template for new features

[msschwartz21]

Note: explain that other types of detections could be incorporated as long as the loader and matcher work together. Once the matching is established, downstream metrics shouldn't care about the type of detection.

[msschwartz21]

As discussed in #129, improve documentation of the intended meaning of missing flags.