fix(docs): syntax error, improve examples

Author: AlvaroBernalG

docs/useMouse.md

@@ -16,10 +16,10 @@ const Demo = () => {
   const {docX, docY, posX, posY, elX, elY, elW, elH} = useMouse(ref);
 
   return (
-    <div ref={element}>
+    <div ref={ref}>
       <div>Mouse position in document - x:{docX} y:{docY}</div>
-      <div>Mouse position in element - x:{posX} y:{posY}</div>
-      <div>Element position - x:{elX} y:{elY}</div>
+      <div>Mouse position in element - x:{elX} y:{elY}</div>
+      <div>Element position- x:{posX} y:{posY}</div>
       <div>Element dimensions - {elW}x{elH}</div>
     </div>
   );