Update rustls exmaple for work with newest updates to the crate. Also README section added to point out the need for this example

Author: Brobb954

README.md

@@ -168,6 +168,11 @@ let mut conn = pool.get().await?;
 let res = users::table.select(User::as_select()).load::(&mut conn).await?;
 ```
 
+## Diesel-Async with Secure Database
+
+In the event of using this crate with a `sslmode=require` flag, it will be necessary to build a TLS cert.
+There is an example provided for doing this using the `rustls` crate in the `postgres` examples folder.
+
 ## Crate Feature Flags
 
 Diesel-async offers several configurable features:

examples/postgres/pooled-with-rustls/src/main.rs

@@ -63,7 +63,6 @@ fn establish_connection(config: &str) -> BoxFuture<ConnectionResult<AsyncPgConne
 fn root_certs() -> rustls::RootCertStore {
     let mut roots = rustls::RootCertStore::empty();
     let certs = rustls_native_certs::load_native_certs().expect("Certs not loadable!");
-    let certs: Vec<_> = certs.into_iter().map(|cert| cert.0).collect();
-    roots.add_parsable_certificates(&certs);
+    roots.add_parsable_certificates(certs);
     roots
 }