verify: Add a README file

Add a brief readme file, point at `cargo run -- --help` and also at the
docs we already wrote in `types/README.md`.

verify/README.md

@@ -0,0 +1,15 @@
+# Verify
+
+TL;DR: `cargo run -- --help`
+
+This crate provides a tool to help verify the rest of the repository.
+Specifically the Single Source Of Truth for a specific Core version is
+the version module in `types` e.g., `types/src/v17/mod.rs`.
+
+Verification is warranted because there are many pieces involved and
+during development much cut'n'paste. We want to catch our mistakes and
+have some confidence that our claims are valid.
+
+Please see `types/README.md` for more information.
+
+