Adjust docs intro caution

Author: williewillus

web/docs/intro.md

@@ -11,4 +11,6 @@ Welcome to Patchouli, a mod aimed at providing High Quality Data-Driven Document
 Because of limited resources, this website is usually targeted only towards the latest version of Minecraft and Patchouli available.
 
 If you need documentation for an older Minecraft version, please use (and donate to!) the
-[Internet Archive Wayback Machine](https://archive.org/).
+[Internet Archive Wayback Machine](https://archive.org/), or if you're comfortable reading
+plain text or compiling the site yourself, visit the `web/` directory of the older
+branches on [GitHub](https://github.com/VazkiiMods/Patchouli/tree/master/web).