fix(docs): correct Discourse icon filename in footer social links

Author: fassko

src/theme/Footer/SocialLinks/SocialLinks.tsx

@@ -5,7 +5,7 @@ import Discord from "@site/static/img/social-icons/discord.svg";
 import Medium from "@site/static/img/social-icons/Medium.svg";
 import X from "@site/static/img/social-icons/X.svg";
 import Telegram from "@site/static/img/social-icons/Telegram.svg";
-import Discourse from "@site/static/img/social-icons/Discourse.svg";
+import Discourse from "@site/static/img/social-icons/discourse.svg";
 
 import Link from "@docusaurus/Link";
 import classes from "./socialLinks.module.css";