Vendor dependencies

vendor/github.com/aws/aws-sdk-go-v2/internal/sync/singleflight/docs.go

@@ -0,0 +1,7 @@
+// Package singleflight provides a duplicate function call suppression
+// mechanism. This package is a fork of the Go golang.org/x/sync/singleflight
+// package. The package is forked, because the package a part of the unstable
+// and unversioned golang.org/x/sync module.
+//
+// https://github.com/golang/sync/tree/67f06af15bc961c363a7260195bcd53487529a21/singleflight
+package singleflight