x/pkgsite: godoc.org redirect feedback - tracking issue  #39144

This is an umbrella issue to keep track of issues related to redirecting traffic from godoc.org to pkg.go.dev.

Issues related to this topic:

• go.dev: open source pkg.go.dev #36747: open source pkg.go.dev
• x/pkgsite: support viewing a package @master #36811: support viewing a package@master
• x/pkgsite: examples missing playground links #36865: examples missing playground links
• go.dev: add support for bookmarklet to navigate from repository to doc #36929: add support for bookmarklet to navigate from repository to doc
• x/pkgsite: serve status badge similar to godoc.org #36982: serve status badge similar to godoc.org
• x/pkgsite: automatically fetch a requested package if it does not exist on pkg.go.dev #37002: automatically fetch a requested package if it does not exist on pkg.go.dev
• go.dev: support package owner-initiated redirect from godoc.org to pkg.go.dev #37099: support package owner-initiated redirect from godoc.org to pkg.go.dev
• x/pkgsite: missing source files listing #37863: missing source files listing
• x/pkgsite: automatically link RFCs in package documentation #38056: automatically link RFCs in package documentation
• x/pkgsite: incorrect rendering of fixed-size unicode box-drawing characters on Firefox #38763: incorrect rendering of fixed-size unicode box-drawing characters
• x/pkgsite: slower loads than godoc.org #38892: slower loads than godoc.org
• x/pkgsite: Missing links to source code for git.sr.ht #38986: missing links to source code for git.sr.ht
• x/pkgsite: documentation misparsed as an anchor #39270: documentation misparsed as an anchor
• x/pkgsite: missing documentation headings/anchors #39529: missing documentation headings/anchors

At the moment, our priority is to work towards open sourcing (#36747) and to address design feedback. We will plan to address the issues above before redirecting traffic from godoc.org to pkg.go.dev.

/cc @jba @spf13 @fflewddur @Joanne881107