make sed template call deprecated

and link to docs

template/interpolate/funcs.go

@@ -40,6 +40,7 @@ var FuncGens = map[string]interface{}{
 	"packer_version": funcGenPackerVersion,
 	"consul_key":     funcGenConsul,
 	"vault":          funcGenVault,
+	"sed":            funcGenSed,
 
 	"replace":     replace,
 	"replace_all": replace_all,
@@ -266,6 +267,14 @@ func funcGenVault(ctx *Context) interface{} {
 	}
 }
 
+func funcGenSed(ctx *Context) interface{} {
+	return func(expression string, inputString string) (string, error) {
+		return "", errors.New("template function `sed` is deprecated " +
+			"use `replace` or `replace_all` instead." +
+			"Documentation: https://www.packer.io/docs/templates/engine.html")
+	}
+}
+
 func replace_all(old, new, src string) string {
 	return strings.ReplaceAll(src, old, new)
 }