Clean up some small mistakes (#2451)

docs/design/generics/details.md

@@ -3761,7 +3761,7 @@ To define these `impl`s inline in a `class` definition, include a `forall`
 clause with a more-specific type between the `impl` and `as` keywords.
 
 ```
-class Array(T:! Type, template N:! Int) {
+class Array(T:! Type, template N:! i64) {
   impl forall [P:! Printable] Array(P, N) as Printable { ... }
 }
 ```
@@ -5690,7 +5690,7 @@ class Optional(T:! Movable) {
     return {.storage = U.MakeNone()};
   }
   fn Some(x: T) -> Self {
-    return {.storage = u.Make(x)};
+    return {.storage = U.Make(x)};
   }
   ...
   private var storage: U.Storage;

proposals/p0818.md

@@ -259,7 +259,7 @@ interface I {
   let SwapType:! I where .A == B and .B == A and .C == C
                      and .D == D and .E == E;
   let CycleType:! I where .A == B and .B == C and .C == D
-                      and .D == E and .E ==  A;
+                      and .D == E and .E == A;
   fn LookUp(hm: HashMap(D, E)*) -> E;
   fn Foo(x: Bar(A, B));
 }