Remove stale comments on Stream.Can properties (#4506)

Author: stephentoub

xml/System.IO/Stream.xml

@@ -382,8 +382,6 @@
 ## Remarks  
  If a class derived from <xref:System.IO.Stream> does not support reading, calls to the <xref:System.IO.Stream.Read%2A>, <xref:System.IO.Stream.ReadByte%2A>, and <xref:System.IO.Stream.BeginRead%2A> methods throw a <xref:System.NotSupportedException>.  
   
- If the stream is closed, this property returns `false`.  
-  
    
   
 ## Examples  
@@ -446,8 +444,6 @@
 ## Remarks  
  If a class derived from <xref:System.IO.Stream> does not support seeking, calls to <xref:System.IO.Stream.Length%2A>, <xref:System.IO.Stream.SetLength%2A>, <xref:System.IO.Stream.Position%2A>, and <xref:System.IO.Stream.Seek%2A> throw a <xref:System.NotSupportedException>.  
   
- If the stream is closed, this property returns `false`.  
-  
  ]]></format>
         </remarks>
         <related type="Article" href="/dotnet/standard/io/">File and Stream I/O</related>
@@ -557,8 +553,6 @@
 ## Remarks  
  If a class derived from <xref:System.IO.Stream> does not support writing, a call to <xref:System.IO.Stream.Write%2A>, <xref:System.IO.Stream.BeginWrite%2A>, or <xref:System.IO.Stream.WriteByte%2A> throws a <xref:System.NotSupportedException>. In such cases, <xref:System.IO.Stream.Flush%2A> is typically implemented as an empty method to ensure full compatibility with other <xref:System.IO.Stream> types since it's valid to flush a read-only stream.
   
- If the stream is closed, this property returns `false`.  
-  
    
   
 ## Examples