FAQ Entry for Passwords on JKS / PKCS#12

[SgtCoDFish]

We [1] generally agree that passwords on JKS / PKCS#12 files solve no problems in any practical threat model when using cert-manager or trust-manager. That can be incredbly unintuitive for users who see the word "password" and assume it must be a security feature.

We should document why we take the position that this is not a meaningful security feature on the website, so we can refer people to that text.

[1]: This was discussed in our standup on 2023-11-17