Update to bdk-ffi 0.6.0

Author: notmandatory

README.md

@@ -45,8 +45,10 @@ own Github repository use the following steps:
 
 1. Install required targets.
    ```shell
-    rustup target add aarch64-apple-ios x86_64-apple-ios
-    ```
+   rustup target add aarch64-apple-ios x86_64-apple-ios
+   rustup target add aarch64-apple-ios-sim --toolchain nightly 
+   rustup component add rust-src --toolchain nightly-aarch64-apple-darwin
+   ```
 
 1. Build [`bdk-ffi`] Swift bindings and `bdkFFI.xcframework.zip`.
    ```shell