Revise tagline for site update announcement

Updated the tagline to reflect upcoming changes and warn about potential outdated content.

Author: ukdaaan

src/content/docs/index.mdx

@@ -3,7 +3,7 @@ title: Minecraft Admin Wiki
 description: We're setup.md, the Minecraft administration wiki, written by enthusiasts and targeted to the novice.
 template: splash
 hero:
-  tagline: Your home of good information written by enthusiasts for the novice Minecraft server owner.
+  tagline: Big news! We're giving the whole site a glow-up that you'll see soon! In the meantime, we're keeping these V3 docs up, but just a quick warning: some pages might be a tiny bit out of date.
   image:
     file: '@assets/houston.webp'
   actions: