docs: add examples and update README.md

examples/merge_data.py

@@ -0,0 +1,19 @@
+import asyncio
+
+from mihomo import Language, MihomoAPI, tools
+
+
+async def main():
+    client = MihomoAPI(language=Language.EN)
+    old_data = await client.fetch_user(800333171)
+
+    # Change characters in game and wait for the API to refresh
+    # ...
+
+    new_data = await client.fetch_user(800333171)
+    data = tools.merge_character_data(new_data, old_data)
+
+    print(data)
+
+
+asyncio.run(main())