Remove incorrect statement from ThreadLocal docs (#3316)

Author: stephentoub

xml/System.Threading/ThreadLocal`1.xml

@@ -524,7 +524,7 @@
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 ## Remarks  
- If this instance was not previously initialized for the current thread, accessing <xref:System.Threading.ThreadLocal%601.Value%2A> will attempt to initialize it. If an initialization function was supplied during the construction, that initialization will happen by invoking the function to retrieve the initial value for <xref:System.Threading.ThreadLocal%601.Value%2A>. Otherwise, the default value of will be used. If an exception is thrown, that exception is cached and thrown on each subsequent access of the property.  
+ If this instance was not previously initialized for the current thread, accessing <xref:System.Threading.ThreadLocal%601.Value%2A> will attempt to initialize it. If an initialization function was supplied during the construction, that initialization will happen by invoking the function to retrieve the initial value for <xref:System.Threading.ThreadLocal%601.Value%2A>. Otherwise, the default value of `T` will be used.  
   
  ]]></format>
         </remarks>