Docs: Fix SmartPointers.md undefined article and double word

Documentation/SmartPointers.md

@@ -16,7 +16,7 @@ These pointers cannot be copied. Transferring ownership is done by moving the po
 
 `NonnullOwnPtr` is a special variant of `OwnPtr` with one additional property: it cannot be null. `NonnullOwnPtr` is suitable as a return type from functions that are guaranteed to never return null, and as an argument type where ownership is transferred, and the argument may not be null. In other words, if `OwnPtr` is "\*", then `NonnullOwnPtr` is "&".
 
-Note: A `NonnullOwnPtr` can be assigned to an `OwnPtr` but not vice versa. To transform an known-non-null `OwnPtr` into a `NonnullOwnPtr`, use `OwnPtr::release_nonnull()`.
+Note: A `NonnullOwnPtr` can be assigned to an `OwnPtr` but not vice versa. To transform a known-non-null `OwnPtr` into a `NonnullOwnPtr`, use `OwnPtr::release_nonnull()`.
 
 ### Construction using helper functions
 
@@ -83,7 +83,7 @@ class Bar : public RefCounted<Bar> {
 };
 ```
 
-Note: A `NonnullRefPtr` can be assigned to a `RefPtr` but not vice versa. To transform an known-non-null `RefPtr` into a `NonnullRefPtr`, either use `RefPtr::release_nonnull()` or simply dereference the `RefPtr` using its `operator*`.
+Note: A `NonnullRefPtr` can be assigned to a `RefPtr` but not vice versa. To transform a known-non-null `RefPtr` into a `NonnullRefPtr`, either use `RefPtr::release_nonnull()` or simply dereference the `RefPtr` using its `operator*`.
 
 ### Construction using helper functions
 
@@ -120,7 +120,7 @@ NonnullRefPtr<Bar> our_object = adopt_ref(*new Bar);
 
 Note: It is safe to immediately dereference this raw pointer, as the normal `new` expression cannot return a null pointer.
 
-Any (possibly null) pointer to a reference-counted object can can be turned into a `RefPtr` by the global `adopt_ref_if_nonnull()` function.
+Any (possibly null) pointer to a reference-counted object can be turned into a `RefPtr` by the global `adopt_ref_if_nonnull()` function.
 
 ```cpp
 RefPtr<Bar> our_object = adopt_ref_if_nonnull(new (nothrow) Bar);