Fix README.md examples based on feedback - remove hardcoded paths, unused imports, type errors, and add cargo config info

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

Author: Copilot

README.md

@@ -42,7 +42,7 @@ use hyperlight_host::{MultiUseSandbox, UninitializedSandbox};
 fn main() -> hyperlight_host::Result<()> {
     // Create an uninitialized sandbox with a guest binary
     let mut uninitialized_sandbox = UninitializedSandbox::new(
-        hyperlight_host::GuestBinary::FilePath(hyperlight_testing::simple_guest_as_string().unwrap()),
+        hyperlight_host::GuestBinary::FilePath("path/to/your/guest/binary".to_string()),
         None // default configuration
     )?;
 
@@ -88,7 +88,7 @@ use hyperlight_common::flatbuffer_wrappers::util::get_flatbuffer_result;
 use hyperlight_guest::error::{HyperlightGuestError, Result};
 use hyperlight_guest_bin::guest_function::definition::GuestFunctionDefinition;
 use hyperlight_guest_bin::guest_function::register::register_function;
-use hyperlight_guest_bin::host_comm::{call_host_function, call_host_function_without_returning_result};
+use hyperlight_guest_bin::host_comm::call_host_function;
 
 fn print_output(function_call: &FunctionCall) -> Result<Vec<u8>> {
     if let ParameterValue::String(message) = function_call.parameters.clone().unwrap()[0].clone() {
@@ -112,7 +112,7 @@ pub extern "C" fn hyperlight_main() {
         "PrintOutput".to_string(),
         Vec::from(&[ParameterType::String]),
         ReturnType::Int,
-        print_output as i64,
+        print_output as usize,
     );
     register_function(print_output_def);
 }
@@ -127,6 +127,28 @@ pub fn guest_dispatch_function(function_call: FunctionCall) -> Result<Vec<u8>> {
 }
 ```
 
+**Note**: Guest applications require a specific build configuration. Create a `.cargo/config.toml` file in your guest project with the following content:
+
+```toml
+[build]
+target = "x86_64-unknown-none"
+
+[target.x86_64-unknown-none]
+rustflags = [
+  "-C",
+  "code-model=small",
+  "-C",
+  "link-args=-e entrypoint",
+]
+linker = "rust-lld"
+
+[profile.release]
+panic = "abort"
+
+[profile.dev]
+panic = "abort"
+```
+
 For additional examples of using the Hyperlight host Rust library, see
 the [./src/hyperlight_host/examples](./src/hyperlight_host/examples) directory.