Update Building_An_Activity.mdx (discord#7228)

Author: userandaname

docs/activities/Building_An_Activity.mdx

@@ -235,7 +235,7 @@ document.querySelector('#app').innerHTML = `
 </Collapsible>
 
 > warn
-> **Time to leave your browser behind**<br />Once you add the SDK to your app, you will **not** be able to view your app inside your web browser. In the next step, we will run your Activity inside of Discord. In the next step, we will go over how to view you app in Discord.
+> **Time to leave your browser behind**<br />Once you add the SDK to your app, you will **not** be able to view your app inside your web browser. In the next step, we will run your Activity inside of Discord. In the next step, we will go over how to view your app in Discord.
 
 <Collapsible title="Step 3 Checkpoint" icon="list" open>