Fix a couple of typos (#345)

Author: waywardmonkeys

fluent-fallback/README.md

@@ -2,7 +2,7 @@
 
 `fluent-fallback` is a Rust implementation of the [Project Fluent][] higher level API.
 
-The `Localization` struct encapsulates a persistant localization context providing
+The `Localization` struct encapsulates a persistent localization context providing
 language fallbacking. The instance remains available throughout the whole life cycle of
 the corresponding UI, reacting to events such as locale changes, resource updates etc.
 

intl-memoizer/src/lib.rs

@@ -89,7 +89,7 @@ pub trait Memoizable {
 ///     /// will be used as a prefix to the formatting operation.
 ///     type Args = (String,);
 ///
-///     /// If the construtor is fallible, than errors can be described here.
+///     /// If the constructor is fallible, than errors can be described here.
 ///     type Error = ();
 ///
 ///     /// This function wires together the `Args` and `Error` type to construct