Documentation around supported Alibi Algorithms

[FarrandTom]

Proposal

Use case. Why is this important?
Currently, it is not easy to find which of the Alibi algorithms (outlier and drift detectors, plus explainers) are supported within Seldon Core. There is this page which documents the explainers supported but I do not think it is particularly discoverable and informative past listing the algorithm names themselves. Therefore I believe there should be a documentation page which explicitly lists those which are supported and provides a similar algorithm overview as found in the docs for Alibi here and here.