Update Mutex.xml (#4553)

maybe it's a typo

Author: hecongy

xml/System.Threading/Mutex.xml

@@ -81,7 +81,7 @@
 
   
 ## Examples  
- This example shows how a local <xref:System.Threading.Mutex> object is used to synchronize access to a protected resource. Because each calling thread is blocked until it acquires ownership of the mutex, it must call the <xref:System.Threading.Mutex.ReleaseMutex%2A> method to release ownership of the thread.  
+ This example shows how a local <xref:System.Threading.Mutex> object is used to synchronize access to a protected resource. Because each calling thread is blocked until it acquires ownership of the mutex, it must call the <xref:System.Threading.Mutex.ReleaseMutex%2A> method to release ownership of the mutex.  
   
  [!code-csharp[System.Threading.Mutex.Class#1](~/samples/snippets/csharp/VS_Snippets_CLR_System/system.threading.mutex.class/cs/example1.cs#1)]
  [!code-vb[System.Threading.Mutex.Class#1](~/samples/snippets/visualbasic/VS_Snippets_CLR_System/system.threading.mutex.class/vb/example1.vb#1)]