Documentation tweaks

Co-authored-by: Andreas Fackler <afck@users.noreply.github.com>
Signed-off-by: James Kay <twey@twey.co.uk>

linera-client/src/persistent/mod.rs

@@ -33,9 +33,9 @@ pub use memory::Memory;
 pub trait LocalPersist: Deref {
     type Error: std::error::Error + Send + Sync + 'static;
 
-    /// Get a mutable reference to the value.  This is not expressed as a
+    /// Gets a mutable reference to the value. This is not expressed as a
     /// [`DerefMut`](std::ops::DerefMut) bound because it is discouraged to consume this
-    /// function!  Instead, use `mutate`.
+    /// function! Instead, use `mutate`.
     fn as_mut(&mut self) -> &mut Self::Target;
 
     /// Saves the value to persistent storage.