docs: updated key size in transit documentation (hashicorp#19346)

website/content/api-docs/secret/transit.mdx

@@ -79,7 +79,7 @@ values set here cannot be changed after key creation.
      `managed_key_id` parameter must be specified.
 - `key_size` `(int: "0", optional)` - The key size in bytes for algorithms
   that allow variable key sizes.  Currently only applicable to HMAC, where
-  it must be between 16 and 512 bytes.
+  it must be between 32 and 512 bytes.
 - `auto_rotate_period` `(duration: "0", optional)` – The period at which
   this key should be rotated automatically. Setting this to "0" (the default)
   will disable automatic key rotation. This value cannot be shorter than one