Upgrade to github.com/russross/blackfriday/v2

cmd/sitesearch/sitesearch.go

go.mod

go.sum

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

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

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

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

vendor/github.com/russross/blackfriday/v2/.gitignore

vendor/github.com/russross/blackfriday/v2/.travis.yml

vendor/github.com/russross/blackfriday/v2/LICENSE.txt

vendor/github.com/russross/blackfriday/v2/README.md

vendor/github.com/russross/blackfriday/v2/block.go

vendor/github.com/russross/blackfriday/v2/doc.go

vendor/github.com/russross/blackfriday/v2/entities.go

vendor/github.com/russross/blackfriday/v2/esc.go

vendor/github.com/russross/blackfriday/v2/go.mod

vendor/github.com/russross/blackfriday/v2/html.go

vendor/github.com/russross/blackfriday/v2/inline.go

vendor/github.com/russross/blackfriday/v2/markdown.go

vendor/github.com/russross/blackfriday/v2/node.go