cmd/go: fix 'go help mod edit' JSON documentation

The object representing a module directive may have a "Deprecated"
field but not a "Version" field. Other objects representing module
versions have "Path" and "Version" fields but not "Deprecated".

For #40357

Change-Id: Iad8063dfa6f7ceea22981a8a8f99e65fa3b7ffa0
Reviewed-on: https://go-review.googlesource.com/c/go/+/309337
Trust: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

src/cmd/go/internal/modcmd/edit.go

@@ -85,19 +85,24 @@ The -json flag prints the final go.mod file in JSON format instead of
 writing it back to go.mod. The JSON output corresponds to these Go types:
 
 	type Module struct {
-		Path string
-		Deprecated string
+		Path    string
+		Version string
 	}
 
 	type GoMod struct {
-		Module  Module
+		Module  ModPath
 		Go      string
 		Require []Require
 		Exclude []Module
 		Replace []Replace
 		Retract []Retract
 	}
 
+	type ModPath struct {
+		Path       string
+		Deprecated string
+	}
+
 	type Require struct {
 		Path string
 		Version string