general: move from godoc.org to pkg.go.dev for documentation

Per https://blog.golang.org/godoc.org-redirect, godoc traffic will soon
be redirected automatically to pkg.go.dev.

Per the most recent golang-tools call, there is now a push to update
badges/links from godoc.org to pkg.go.dev.

pkg.go.dev is a far superior documentation experience for the CUE docs,
and there are no known blockers/issues that would prevent us migrating.

Most importantly we get a new badge.

Change-Id: Icf3ab495a69a031e5fb141440ba2f296643d5cf6
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/8234
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>

README.md

@@ -13,7 +13,7 @@
  See the License for the specific language governing permissions and
  limitations under the License.
 -->
-[![GoDoc](https://godoc.org/cuelang.org/go?status.svg)](https://godoc.org/cuelang.org/go)
+[![Go Reference](https://pkg.go.dev/badge/cuelang.org/go.svg)](https://pkg.go.dev/cuelang.org/go)
 [![Github](https://github.com/cuelang/cue/workflows/Test/badge.svg)](https://github.com/cuelang/cue/actions)
 [![GolangCI](https://golangci.com/badges/github.com/cuelang/cue.svg)](https://golangci.com/r/github.com/cuelang/cue)
 [![Go 1.13+](https://img.shields.io/badge/go-1.13-9cf.svg)](https://golang.org/dl/)
@@ -125,9 +125,9 @@ an existing set of Kubernetes configurations is available in
 
 - [Language Specification](./doc/ref/spec.md): official CUE Language specification.
 
-- [API](https://godoc.org/cuelang.org/go/cue): the API on godoc.org
+- [API](https://pkg.go.dev/cuelang.org/go/cue): the API on pkg.go.dev
 
-- [Builtin packages](https://godoc.org/cuelang.org/go/pkg): builtins available from CUE programs
+- [Builtin packages](https://pkg.go.dev/cuelang.org/go/pkg): builtins available from CUE programs
 
 - [`cue` Command line reference](./doc/cmd/cue.md): the `cue` command
 

pkg/tool/cli/gen.go

@@ -17,7 +17,7 @@
 package main
 
 // TODO: remove when we have a cuedoc server. Until then,
-// piggyback on godoc.org.
+// piggyback on pkg.go.dev.
 
 import (
 	"bytes"

pkg/tool/exec/gen.go

@@ -17,7 +17,7 @@
 package main
 
 // TODO: remove when we have a cuedoc server. Until then,
-// piggyback on godoc.org.
+// piggyback on pkg.go.dev.
 
 import (
 	"bytes"

pkg/tool/file/gen.go

@@ -17,7 +17,7 @@
 package main
 
 // TODO: remove when we have a cuedoc server. Until then,
-// piggyback on godoc.org.
+// piggyback on pkg.go.dev.
 
 import (
 	"bytes"

pkg/tool/gen.go

@@ -17,7 +17,7 @@
 package main
 
 // TODO: remove when we have a cuedoc server. Until then,
-// piggyback on godoc.org.
+// piggyback on pkg.go.dev.
 
 import (
 	"bytes"

pkg/tool/http/gen.go

@@ -17,7 +17,7 @@
 package main
 
 // TODO: remove when we have a cuedoc server. Until then,
-// piggyback on godoc.org.
+// piggyback on pkg.go.dev.
 
 import (
 	"bytes"

pkg/tool/os/gen.go

@@ -17,7 +17,7 @@
 package main
 
 // TODO: remove when we have a cuedoc server. Until then,
-// piggyback on godoc.org.
+// piggyback on pkg.go.dev.
 
 import (
 	"bytes"