x/pkgsite: missing `added in` label for type in runtime/cgo package

[jamalc]

What is the URL of the page with the issue?

https://pkg.go.dev/runtime/cgo

Screenshot

What did you expect to see?

A label indicating that type Handle was added in go1.17.

What did you see instead?

No label.

[jamalc]

Its WAI that this label doesn't show on the doc page (https://go.googlesource.com/pkgsite/+/refs/heads/master/internal/godoc/render.go#173). Handle was added in the earliest version of this package containing any API so we hide the label.

• We should probably remove "containing any API" from the consideration: if a package existed but had no API in an earlier version, then it's worth noting when new API was added.
• We should probably mark at the top of package docs the first module version that introduced the package. Both of these are general, not specific to the "Go" module.

Another example to consider: https://pkg.go.dev/net/netip was created in go1.18 and does not include added in go1.18 for any symbols. We might continue to hide the labels for net/netip because this package was new in go1.18.