Added debug=2 in release profile to all examples.

This makes rtt output work right when using `cargo run` in release mode.

Debug was already enabled for release builds in some of the examples but
not all.

examples/stm32wb/Cargo.toml

@@ -52,3 +52,6 @@ required-features = ["ble"]
 [[bin]] 
 name = "gatt_server"
 required-features = ["ble"]
+
+[profile.release]
+debug = 2