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/wasm/Cargo.toml

@@ -17,3 +17,6 @@ wasm-bindgen = "0.2"
 web-sys = { version = "0.3", features = ["Document", "Element", "HtmlElement", "Node", "Window" ] }
 log = "0.4.11"
 critical-section = { version = "1.1", features = ["std"] }
+
+[profile.release]
+debug = 2