add rgb check and example

examples/embassy-rgb-check/build.rs

@@ -0,0 +1,12 @@
+// main: tell Cargo to rerun when memory.x changes and add the shared link path.
+// Input: none.
+// Output: build script side effects only.
+fn main() {
+    println!("cargo:rerun-if-changed=../../memory.x");
+    println!(
+        "cargo:rustc-link-search={}",
+        std::path::PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap())
+            .join("../..")
+            .display()
+    );
+}