fix: mfa generator length is too much and optional (#4813)

Signed-off-by: Gergely Brautigam <182850+Skarlso@users.noreply.github.com>

docs/snippets/generator-mfa.yaml

@@ -3,7 +3,6 @@ kind: MFA
 metadata:
   name: my-mfa-generator
 spec:
-  length: 42
   secret:
     key: token
     name: secret