Add readme to libtransact/Cargo.toml
These should cause more information to be displayed on crates.io.
@@ -4,6 +4,7 @@ version = "0.1.1"
authors = ["Bitwise IO, Inc."]
edition = "2018"
license = "Apache-2.0"
+readme = "../README.md"
description = """\
Transact is a transaction execution platform designed to be used as \
a library or component when implementing distributed ledgers, including \
