cmd/go: add documentation for Embed fields in go list output

This change the struct fields for EmbedPatterns and EmbedFiles
to the Package struct listed in the go list documentation that
specifies the fields available to the go list template.

Fixes #43081

Change-Id: I89c325a9d6292a6ce484ee588b172d2f84e2333a
Reviewed-on: https://go-review.googlesource.com/c/go/+/282195
Trust: Michael Matloob <[email protected]>
Run-TryBot: Michael Matloob <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Bryan C. Mills <[email protected]>
Reviewed-by: Jay Conrod <[email protected]>

Author: matloob

src/cmd/go/alldocs.go

@@ -89,6 +89,10 @@ to -f '{{.ImportPath}}'. The struct being passed to the template is:
         TestGoFiles     []string   // _test.go files in package
         XTestGoFiles    []string   // _test.go files outside package
 
+        // Embedded files
+        EmbedPatterns []string // //go:embed patterns
+        EmbedFiles    []string // files and directories matched by EmbedPatterns
+
         // Cgo directives
         CgoCFLAGS    []string // cgo: flags for C compiler
         CgoCPPFLAGS  []string // cgo: flags for C preprocessor