Document python3 requirement for iOS tests

Add a short note to the iOS getting-started doc that build-tests-ios.sh requires python3 on PATH to parse simctl JSON when resolving the simulator name.

Co-authored-by: Copilot <[email protected]>

Author: bmehta001

docs/cpp-start-ios.md

@@ -20,6 +20,8 @@ Run `build-ios.sh [clean] [release|debug] [arm64|arm64e]`.
 
 Run `./build-tests-ios.sh [release|debug] "<simulator name>"`.
 
+The script requires `python3` on `PATH` to parse `simctl --json` when resolving the simulator name.
+
 Example:
 
 ```sh