Fix up documentation in a few places (and add tree_ attributes).
Fix up documentation in a few places (and add tree_ attributes).

lmcinnes/hdbscan,scikit-learn-contrib/hdbscan,brunoalano/hdbscan,c-north/hdbscan,scikit-learn-contrib/hdbscan,lmcinnes/hdbscan,brunoalano/hdbscan