Fix spurious trailing sentence

Author: gnzlbg

reference/src/layout/unions.md

@@ -57,8 +57,9 @@ assert_eq!(size_of::<U>(), 2);
 # }
 ``**
 
-**Note**: Fields are overlapped instead of laid out sequentially, so unlike structs there is no "between the fields" that could be filled with padding.
-only have trailing padding.
+> **Note**: Fields are overlapped instead of laid out sequentially, so 
+> unlike structs there is no "between the fields" that could be filled 
+> with padding.
 
 The bit `i` of a `repr(C)` union is a padding bit if the bit `i` of each of its
 fields is a padding bit or trailing padding. That is: