Stop referencing --frontend-template

[chadoh]

The Build a Dapp tutorial and Develop contract initialization frontend templates both mention stellar contract init --frontend-template. The --frontend-template option is going away:

• Simplify/improve UX of contract init stellar-cli#1586

The plan is to have people just clone GitHub repos, such as stellar/soroban-template-astro. They will then have their own hard-coded list of contracts, rather than being built to work with an unknown set (which currently come from the list given to the --with-example option to stellar contract init).

Before we remove the option, we need to update all the docs to stop referencing the --frontend-template option, and have them clone the frontend repo instead.

[0xdevcollins]

Hello @chadoh,

Could you please assign this task to me? I would be happy to take it on.

[briwylde08]

#1138