Update black in pre-commit and add blacken-docs.
repos:
- repo: https://github.com/psf/black
- rev: 19.3b0
+ rev: 19.10b0
hooks:
- id: black
+
+- repo: https://github.com/asottile/blacken-docs
+ rev: v1.4.0
+ hooks:
+ - id: blacken-docs
