Add security page including TLS and SST descriptions.

[Jakio815]

No description provided.

[edwardalee]

Looks great! One small point: Perhaps the docs should point out that for proper security, it will be necessary to restrict read permission of the fed-gen and LinguaFrancaRemote folders (the latter on machines that are targets of the deploy scripts). This is because the private keys will appear in these directories.

[Jakio815]

@edwardalee

I added a new warning block.

:::warning[Key Protection & Directory Permissions]
For proper security, you must restrict read permissions for the directories containing the generated private keys. Ensure that read access is restricted to authorized users only for:

1. The local fed-gen directory where the compiler generates the private keys.
2. The LinguaFrancaRemote folder on remote target machines where deployment or remote launch scripts copy and execute the federated binaries.
   Because private keys (.key or SST credentials) are stored within these directories, leaving them readable by others on the host system compromises the entire federation's security.
   :::