[Rules] Update index.mdx

Can we link it to our webpage on Cloudflare plans?

https://www.cloudflare.com/en-gb/plans/

Author: nenizera

src/content/docs/rules/normalization/index.mdx

@@ -27,7 +27,7 @@ URL normalization does not perform any <GlossaryTooltip term="redirect">redirect
 
 ## Availability
 
-URL normalization is available in all Cloudflare plans.
+URL normalization is available in all [Cloudflare plans](https://www.cloudflare.com/en-gb/plans/).
 
 ## Get started