docs OPL: update Hyperlane CLI regrading getStorageAt

[rube-de]

When this PR oasisprotocol/oasis-sdk#2215 is live, getStorageAt will work for the proxy admin slot.

Change Hyperlane CLI docs that the workaround isn't needed anymore.

See also: oasisprotocol/sapphire-paratime#588

[ptrus]

This should now be live on testnet.