doc: fix AES-OCB IV length in SubtleCrypto.supports example

Signed-off-by: anshikakalpana <anshikajain196872@gmail.com>

Author: Anshikakalpana

doc/api/webcrypto.md

@@ -500,7 +500,7 @@ const key = await crypto.subtle.deriveKey(
   ['encrypt', 'decrypt'],
 );
 const plaintext = 'Hello, world!';
-const iv = crypto.getRandomValues(new Uint8Array(16));
+const iv = crypto.getRandomValues(new Uint8Array(12));
 const encrypted = await crypto.subtle.encrypt(
   { name: encryptionAlg, iv },
   key,