Update documentation

Author: nemanjarogic

src/CreationalPatterns/Singleton/Greeter/Types/DoubleCheckGreeter.cs

@@ -6,7 +6,7 @@ namespace Greeter.Types
     /// This implementation attempts to be thread-safe without the necessity of taking out a lock every time.
     /// However, it's easy to get wrong. The pattern needs to be pretty much exactly as above - any significant changes
     /// are likely to impact either performance or correctness.
-    /// It doesn't perform as well as the <see cref="LocklessGreeter"/> or <see cref="LocklessFullyLazyGreeter"/> Types.
+    /// It doesn't perform as well as the <see cref="LocklessGreeter"/> or <see cref="LocklessFullyLazyGreeter"/>.
     /// </summary>
     public class DoubleCheckGreeter : BaseGreeter
     {

src/CreationalPatterns/Singleton/Greeter/Types/LocklessFullyLazyGreeter.cs

@@ -3,8 +3,8 @@
 namespace Greeter.Types
 {
     /// <summary>
-    /// Instantiation is triggered by the first reference to the static member of the nested class, which only occurs in Instance.
-    /// This means the implementation is fully lazy.
+    /// Instantiation is triggered by the first reference to the static member of the nested class,
+    /// which only occurs in Instance property. This means the implementation is fully lazy.
     /// </summary>
     public class LocklessFullyLazyGreeter : BaseGreeter
     {