Link to Go module text files with go-mod-viewer.appspot.com

[alexandear]

Go mod viewer displays text files from Go modules stored in the Go module proxy.

The URL schema is https://go-mod-viewer.appspot.com/<module>@<version>/<file>.
Adding #Lnnn links directly to and highlights line nnn.

For example: https://go-mod-viewer/rsc.io/quote@v1.5.2/README.md#L1

[nikolaydubina]

nice find. lets add this.