Rust: add support for keywords from the 2018 edition

src/rust/rust.ts

@@ -42,11 +42,14 @@ export const language = <languages.IMonarchLanguage>{
 	defaultToken: 'invalid',
 	keywords: [
 		'as',
+		'async',
+		'await',
 		'box',
 		'break',
 		'const',
 		'continue',
 		'crate',
+		'dyn',
 		'else',
 		'enum',
 		'extern',
@@ -71,6 +74,7 @@ export const language = <languages.IMonarchLanguage>{
 		'super',
 		'trait',
 		'true',
+		'try',
 		'type',
 		'unsafe',
 		'use',