[R2] Adding character length restriction for R2 buckets (#22259)

* Adding character length restriction for R2 buckets

* Wording tweak

Author: Oxyjun

src/content/docs/r2/buckets/create-buckets.mdx

@@ -27,6 +27,7 @@ wrangler r2 bucket create your-bucket-name
 
 - Bucket names can only contain lowercase letters (a-z), numbers (0-9), and hyphens (-).
 - Bucket names cannot begin or end with a hyphen.
+- Bucket names can only be between 3-63 characters in length.
 
 The placeholder text is only for the example.