Incorrect comment on NewBufferedWriter?

[ahimelman]

The comment (and docs) to NewBufferedWriter state that "Users must call Close to guarantee all data has been forwarded to the underlying io.Writer": https://github.com/golang/snappy/blob/674baa8c7fc30da5df3074a459494a7e6b427dff/encode.go#L132

However, in looking at the Flush/Close implementations, and their usages in tests, it seems that users only need to call Flush, not Close, which would allow a caller to continue using the buffered writer.