chore(deps): update module russross/blackfriday to v1.6.0

go.mod

go.sum

vendor/github.com/russross/blackfriday/.travis.yml

vendor/github.com/russross/blackfriday/LICENSE.txt

vendor/github.com/russross/blackfriday/README.md

vendor/github.com/russross/blackfriday/block.go

vendor/github.com/russross/blackfriday/go.mod

vendor/github.com/russross/blackfriday/html.go

vendor/github.com/russross/blackfriday/inline.go

vendor/github.com/russross/blackfriday/markdown.go

vendor/modules.txt