[master] Format markdown (#4068)
[master] Format markdown (#4068)

Produced via:
  `prettier --write --prose-wrap=always $(find -name '*.md' | grep -v vendor | grep -v .github | grep -v docs/cmd/)`
/assign grantr matzew n3wscott
/cc grantr matzew n3wscott
knative/eventing,knative/eventing