doc: clean up module help text in configure.ac
doc: clean up module help text in configure.ac

ElementsProject/secp256k1-zkp,ElementsProject/secp256k1-zkp,bitcoin/secp256k1,bitcoin/secp256k1,peterdettman/secp256k1,bitcoin/secp256k1,peterdettman/secp256k1,bitcoin-core/secp256k1,bitcoin/secp256k1,bitcoin-core/secp256k1,bitcoin/secp256k1