implement nip26 delegation.

README.md

@@ -202,6 +202,41 @@ sub.on('event', (event) => {
 })
 ```
 
+### Performing and checking for delegation
+
+```js
+import {nip26, getPublicKey, generatePrivateKey} from 'nostr-tools'
+
+// delegator
+let sk1 = generatePrivateKey()
+let pk1 = getPublicKey(sk1)
+
+// delegatee
+let sk2 = generatePrivateKey()
+let pk2 = getPublicKey(sk2)
+
+// generate delegation
+let delegation = nip26.createDelegation(sk1, {
+  pubkey: pk2,
+  kind: 1,
+  since: Math.round(Date.now() / 1000),
+  until: Math.round(Date.now() / 1000) + 60 * 60 * 24 * 30 /* 30 days */
+})
+
+// the delegatee uses the delegation when building an event
+let event = {
+  pubkey: pk2,
+  kind: 1,
+  created_at: Math.round(Date.now() / 1000),
+  content: 'hello from a delegated key',
+  tags: [['delegation', delegation.from, delegation.cond, delegation.sig]]
+}
+
+// finally any receiver of this event can check for the presence of a valid delegation tag
+let delegator = nip26.getDelegator(event)
+assert(delegator === pk1) // will be null if there is no delegation tag or if it is invalid
+```
+
 Please consult the tests or [the source code](https://github.com/fiatjaf/nostr-tools) for more information that isn't available here.
 
 ### Using from the browser (if you don't want to use a bundler)