add support for v2 hashing algorithm.

update README.md and demo file to be more in sync.
update to v0.10.0.

dist-browser/hashTwt.d.ts

@@ -1,2 +1,3 @@
 import { Twt } from './types.ts';
-export default function hashTwt(twt: Twt): string;
+export type HashableTwt = Pick<Twt, "content" | "created" | "url"> & Partial<Omit<Twt, "content" | "created" | "url">>;
+export default function hashTwt(twt: HashableTwt, version?: number): string;