Add client support for NIP-02 (manage contact lists)

README.md

@@ -192,10 +192,38 @@ event = user.create_event(
 client.publish(event)
 ```
 
+### Creating/updating your contact list
+
+Every new contact list that gets published overwrites the past ones, so it should contain all entries.
+
+```ruby
+# Creating a contact list event with 2 contacts
+update_contacts_event = user.create_event(
+  kind: Nostr::EventKind::CONTACT_LIST,
+  tags: [
+    [
+      "p", # mandatory
+      "32e1827635450ebb3c5a7d12c1f8e7b2b514439ac10a67eef3d9fd9c5c68e245", # public key of the user to add to the contacts
+      "wss://alicerelay.com/", # can be an empty string or can be omitted
+      "alice" # can be an empty string or can be omitted
+    ],
+    [
+      "p", # mandatory
+      "3efdaebb1d8923ebd99c9e7ace3b4194ab45512e2be79c1b7d68d9243e0d2681", # public key of the user to add to the contacts
+      "wss://bobrelay.com/nostr", # can be an empty string or can be omitted
+      "bob" # can be an empty string or can be omitted
+    ],
+  ],
+)
+
+# Send it to the Relay
+client.publish(update_contacts_event)
+```
+
 ## NIPS
 
 - [x] [NIP-01 - Client](https://github.com/nostr-protocol/nips/blob/master/01.md)
-- [ ] [NIP-01 - Relay](https://github.com/nostr-protocol/nips/blob/master/01.md)
+- [x] [NIP-02 - Client](https://github.com/nostr-protocol/nips/blob/master/02.md)
 
 ## Development