docs: update CosmWasm docs for v0.14 and Stargate

[fadeev]

Just some changes to make it work.

docker run --rm -v "$(pwd)":/code \
  --mount type=volume,source="$(basename "$(pwd)")_cache",target=/code/target \
  --mount type=volume,source=registry_cache,target=/usr/local/cargo/registry \
  cosmwasm/workspace-optimizer:0.10.7

appd tx wasm instantiate 1 '{ "name": "xrp", "symbol": "XRP", "decimals": 8, "mint": {"minter": "cosmos1vvvpnffcl4lzk7zfcr5y8zlp7hqmwuvjck2aq0", "cap": "99900000000"}, "initial_balances": [ { "address": "cosmos1vvvpnffcl4lzk7zfcr5y8zlp7hqmwuvjck2aq0", "amount": "12345678000"} ]}' --from alice --label xrp --gas 1000000