fix(API2:2019): restore "Is the API Vulnerable?" item

Author: PauloASilva

2019/en/dist/owasp-api-security-top-10.odt

@@ -24,6 +24,7 @@ An API is vulnerable if it:
 * Accepts unsigned / weakly signed JWT tokens (`"alg":"none"`) / doesn’t
   validate their expiration date.
 * Uses plain text, encrypted, or weakly hashed passwords.
+* Uses weak encryption keys.
 
 ## Example Attack Scenarios