update readme

Signed-off-by: Clécio Varjão <[email protected]>

README.md

@@ -31,4 +31,10 @@ ngrok http "file://${PWD}/tmp"
 ## For running using the mobile app. Open tmp/__qrcode.png to see the generated QR Codes
 export HOLDER_TYPE=manual
 yarn jest --runInBand --detectOpenHandles --forceExit src/basic.test.ts
-```
+```
+
+## Cleanup
+```
+rm -rf tmp/*.json(N) tmp/*.html(N) logs/*.ndjson(N)
+```
+note: `(N)` is [zsh null glob qualifier](https://zsh.sourceforge.io/Doc/Release/Expansion.html#Glob-Qualifiers)