internal/lsp/helper: fix misspelled "Code generated" comment

...as defined by https://go.dev/s/generatedcode.

Change-Id: Ia6fee7f28a540d2a4a05590887fa78af19d5fc7e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/540217
Reviewed-by: Peter Weinberger <pjw@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: adonovan

gopls/internal/lsp/helper/helper.go

@@ -57,7 +57,7 @@ var tmpl = `// Copyright 2021 The Go Authors. All rights reserved.
 
 package lsp
 
-// code generated by helper. DO NOT EDIT.
+// Code generated by gopls/internal/lsp/helper. DO NOT EDIT.
 
 import (
 	"context"