docs: update workspace README

* Add webpki-root-certs and describe why you should probably prefer
  webpki-roots
* Removes the regenerating sources information - this is covered by each
  individual crate's README. The Warning is left since this is valuable
  top-level context to remember for each crate.

README.md

@@ -1,10 +1,14 @@
-This workspace contains the crates webpki-roots and webpki-ccadb.
+This workspace contains the crates `webpki-roots`, `webpki-root-certs` and `webpki-ccadb`.
 
-The webpki-roots crate contains Mozilla's root certificates for use with
-the [webpki](https://github.com/rustls/webpki) or
-[rustls](https://github.com/rustls/rustls) crates.
+The `webpki-roots` crate contains Mozilla's trusted root certificates for use with
+the [webpki](https://github.com/rustls/webpki) or [rustls](https://github.com/rustls/rustls) crates.
 
-The webpki-ccadb crate populates the root certificates for the webpki-roots crate
+The `webpki-root-certs` is similar to `webpki-roots`, but for use with other projects
+that require the full self-signed X.509 certificate for each trusted root. This is
+unnecessary overhead for `webpki` and `rustls` and you should prefer using
+`webpki-roots` for these projects.
+
+The `webpki-ccadb` crate populates the root certificates for the webpki-roots crate
 using the data provided by the [Common CA Database (CCADB)](https://www.ccadb.org/).
 Inspired by [certifi.io](https://certifi.io/en/latest/).
 
@@ -13,7 +17,7 @@ Inspired by [certifi.io](https://certifi.io/en/latest/).
 
 # Warning
 
-This library is suitable for use in applications that can always be recompiled and instantly deployed.
+These libraries are suitable for use in applications that can always be recompiled and instantly deployed.
 For applications that are deployed to end-users and cannot be recompiled, or which need certification
 before deployment, consider a library that uses the platform native certificate verifier such as
 [rustls-platform-verifier]. This has the additional benefit of supporting OS provided CA constraints
@@ -22,11 +26,6 @@ and revocation data.
 [rustls-platform-verifier]: https://docs.rs/rustls-platform-verifier
 
 # License
-The underlying data is MPL-licensed, and `webpki-roots/src/lib.rs`
-is therefore a derived work.
 
-# Regenerating sources
-Sources are generated in an integration test, in `webpki-roots/tests/codegen.rs`. The test
-will fail if the sources are out of date relative to upstream, and update
-`webpki-roots/src/lib.rs` if so. The code is generated in deterministic order so changes
-to the source should only result from upstream changes.
+The underlying data is MPL-licensed, and the data in `webpki-roots` and `webpki-root-certs`
+is therefore a derived work.