docs: update API examples with new handle parameter

Updated documentation examples for:
-from_single_file
-from_file
-from_memory

Added None as handle parameter to match new API signature.

Author: ridmii

source/ports/rs_port/src/load.rs

@@ -100,7 +100,7 @@ impl Drop for Handle {
 /// Loads a file from a single file. Usage example: ...
 /// ```
 /// // A Nodejs path
-/// metacall::load::from_single_file("node", "index.js").unwrap();
+/// metacall::load::from_single_file(Tag::NodeJS, "index.js",None).unwrap();
 /// ```
 pub fn from_single_file(
     tag: Tag,
@@ -113,7 +113,7 @@ pub fn from_single_file(
 /// Loads a path from file. Usage example: ...
 /// ```
 /// // A Nodejs script
-/// metacall::load::from_file(Tag::NodeJS, ["index.js", "main.js"]).unwrap();
+/// metacall::load::from_file(Tag::NodeJS, ["index.js", "main.js"],None).unwrap();
 /// ```
 pub fn from_file(
     tag: Tag,
@@ -167,7 +167,7 @@ pub fn from_file(
 /// let script = "function greet() { return 'hi there!' }; module.exports = { greet };";
 ///
 /// // A Nodejs script
-/// metacall::load::from_memory(Tag::NodeJS, script).unwrap();
+/// metacall::load::from_memory(Tag::NodeJS, script, None).unwrap();
 /// ```
 pub fn from_memory(
     tag: Tag,