refactor(website): correct minor spelling error (#2790)

Author: n-zngr

website/versioned_docs/version-8.10.1/advanced-guides/custom-modifiers.mdx

@@ -71,12 +71,12 @@ The `today` modifier is added to the current date:
 
 ```tsx
 function ModifiersToday() {
-  const initialFooter = <p>Try clicking the today’s date.</p>;
+  const initialFooter = <p>Try clicking today’s date.</p>;
   const [footer, setFooter] = useState(initialFooter);
 
   const handleDayClick: DayMouseEventHandler = (day, modifiers) => {
     if (modifiers.today) {
-      setFooter(<p>You clicked the today’s date.</p>);
+      setFooter(<p>You clicked today’s date.</p>);
     } else {
       setFooter(initialFooter);
     }