Add semi colon on the docs.

The run statement returns `()` so it is easier to copy/paste it if it has the semicolon

api/sixtyfps-rs/lib.rs

@@ -43,7 +43,7 @@ sixtyfps::sixtyfps!{
 }
 fn main() {
 #   return; // Don't run a window in an example
-    HelloWorld::new().run()
+    HelloWorld::new().run();
 }
 ```
 
@@ -82,7 +82,7 @@ Then in your main file
 ```ignore
 sixtyfps::include_modules!();
 fn main() {
-    HelloWorld::new().run()
+    HelloWorld::new().run();
 }
 ```