update generated Mainnet and Testnet setting files

[hugo-stacks]

clarinet new automatically generates setting files for mainnet and testnet

https://github.com/stx-labs/clarinet/blob/66679d4de2958e217db5d4b46cbece8cdcaf02f9/components/clarinet-cli/src/generate/project.rs#L193-L222

Instead of asking to set the mnemonic, they should encourage setting an encrypting mnemonic. This could include a comment that explain that they needs to use clarinet deployments encrypt

[linear[bot]]

CNET-169