fix free turnstile widget count (cloudflare#22691)

Author: patriciasantaana

src/content/docs/turnstile/concepts/widget.mdx

@@ -26,7 +26,7 @@ Customers with Enterprise Bot Management and Enterprise Turnstile have the abili
 
 ## Availability
 
-Free users are limited to 10 widgets per account.
+Free users are limited to 20 widgets per account.
 
 Customers with Enterprise Bot Management and Enterprise Turnstile can have this limit increased. Contact your account team to increase your widget limit.