running_on_testnet documentation significantly out of date

[Jackalgirl]

Since the update to Dynamic TAO, the instructions for running a subnet template on testnet are significantly out of date. https://github.com/opentensor/bittensor-subnet-template/blob/main/docs/running_on_staging.md references using the btcli root command, which is no longer present in bittensor-cli. Please update so that this makes sense for users who are attempting to test out the subnet template on testnet, thanks!

[adysingh5711]

Hi @Jackalgirl
I mistakenly opened a pull request for this at #168, before looking on this open issue. Would like to update the documentation, could you please assign it to me.