Update docs with more howto examples (#968)

Co-authored-by: Teemu R. <tpr@iki.fi>

docs/source/codeinfo.md

@@ -0,0 +1,26 @@
+
+:::{note}
+The library is fully async and methods that perform IO need to be run inside an async coroutine.
+Code examples assume you are following them inside `asyncio REPL`:
+```
+    $ python -m asyncio
+```
+Or the code is running inside an async function:
+```py
+import asyncio
+from kasa import Discover
+
+async def main():
+    dev = await Discover.discover_single("127.0.0.1",username="un@example.com",password="pw")
+    await dev.turn_on()
+    await dev.update()
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```
+**All of your code needs to run inside the same event loop so only call `asyncio.run` once.**
+
+*The main entry point for the API is {meth}`~kasa.Discover.discover` and
+{meth}`~kasa.Discover.discover_single` which return Device objects.
+Most newer devices require your TP-Link cloud username and password, but this can be omitted for older devices.*
+:::