docs: emphasize that LLVM binaries must be found in PATH

Signed-off-by: Melvin Wang <[email protected]>

README.md

@@ -23,7 +23,8 @@ This project was built with support of WDM, KMDF, and UMDF drivers in mind, as w
 ### Build Requirements
 
 * Binding generation via `bindgen` requires `libclang`. The easiest way to acquire this is via `winget`
-  * `winget install LLVM.LLVM`
+  * `winget -i install LLVM.LLVM`
+    * Ensure you select the GUI option to add LLVM to the PATH 
 * To execute post-build tasks (ie. `inf2cat`, `infverif`, etc.), `cargo make` is used
   * `cargo install --locked cargo-make --no-default-features --features tls-native`