[CopperLaunch] Improve testnet docs

[crisog]

https://docs.alchemist.wtf/copper/auction-creators/getting-test-tokens-for-balancer-lbps-on-the-kovan-testnet

In the GETTING TOKENS SECTION there are instructions to get testnet tokens from Balancer Pools. There pools are always empty and Balancer has a faucet that's not really visible unless you go ask on Balancer discord.

This is the URL for the faucet: https://balancer-faucet.on.fleek.co/#/faucet

It would be useful if this faucet was included in the docs.

Thank you in advance!