jsgen: proper jsdoc for namespace

vlib/v/gen/js/js.v

@@ -99,7 +99,7 @@ pub fn gen(files []ast.File, table &table.Table, pref &pref.Preferences) string
 	g.finish()
 	mut out := g.hashes() + g.definitions.str() + g.constants.str()
 	for node in deps_resolved.nodes {
-		out += '/* namespace: $node.name */\n'
+		out += g.doc.gen_namespace(node.name)
 		out += 'const $node.name = (function ('
 		imports := g.namespace_imports[node.name]
 		for i, key in imports.keys() {

vlib/v/gen/js/jsdoc.v

@@ -96,3 +96,9 @@ fn (mut d JsDoc) gen_fn(it ast.FnDecl) string {
 	d.write('*/')
 	return d.out.str()
 }
+
+fn (mut d JsDoc) gen_namespace(ns string) string {
+	d.reset()
+	d.writeln('/** @namespace ${ns} */')
+	return d.out.str()
+}