no more double space

Author: RalfJung

src/items/unions.md

@@ -30,21 +30,21 @@ let u = MyUnion { f1: 1 };
 ```
 
 The expression above creates a value of type `MyUnion` and initializes the
-storage using field `f1`.  The union can be accessed using the same syntax as
+storage using field `f1`. The union can be accessed using the same syntax as
 struct fields:
 
 ```rust,ignore
 let f = u.f1;
 ```
 
-Unions have no notion of an "active field".  Instead, every union access just
-interprets the storage at the type of the field used for the access.  Reading a
+Unions have no notion of an "active field". Instead, every union access just
+interprets the storage at the type of the field used for the access. Reading a
 union field is equivalent to a [`transmute`]: The data in the union, no matter
-how it was stored there, is transmuted to the type of the field.  Just like with
+how it was stored there, is transmuted to the type of the field  Just like with
 any other transmute, it is the programmer's responsibility to make sure that the
-data is valid for the field type.  Failing to do so results in undefined
+data is valid for the field type. Failing to do so results in undefined
 behavior (for example, reading the value `3` at type `bool` is undefined
-behavior).  For this reason, all reads of union fields have to be placed in
+behavior). For this reason, all reads of union fields have to be placed in
 `unsafe` blocks:
 
 ```rust