Fix documentation link in readme (#93)

Author: antonydenyer

README.md

@@ -9,7 +9,7 @@ A modular Go implementation of an ERC-4337 Bundler.
 
 # Running an instance
 
-See the `Bundler` documentation at [docs.stackup.sh](https://docs.stackup.sh/docs/category/bundler).
+See the `Bundler` documentation at [docs.stackup.sh](https://docs.stackup.sh/docs/packages/bundler/introduction).
 
 # Contributing