Fix typos in bevy_reflect readme (bevyengine#5134)

# Objective

Fix some typos in bevy_reflect's readme

## Solution

- Change `Foo`'s `d` field to be of type `Vec<Baz>`
- Format `&dyn Reflect` to be monospace

crates/bevy_reflect/README.md

@@ -21,7 +21,7 @@ struct Foo {
     a: u32,
     b: Bar,
     c: Vec<i32>,
-    d: Vec<Bar>,
+    d: Vec<Baz>,
 }
 
 // this will automatically implement the Reflect trait and the TupleStruct trait (because the type is a tuple struct)
@@ -107,7 +107,7 @@ assert!(foo.reflect_partial_eq(&dynamic_struct).unwrap());
 
 ### Trait "reflection"
 
-Call a trait on a given &dyn Reflect reference without knowing the underlying type!
+Call a trait on a given `&dyn Reflect` reference without knowing the underlying type!
 
 ```rust ignore
 #[derive(Reflect)]