Update ProcessStartInfo.xml

Author: AArnott

xml/System.Diagnostics/ProcessStartInfo.xml

@@ -732,7 +732,7 @@ If you use this property to set command-line arguments, <xref:System.Diagnostics
       </ReturnValue>
       <Docs>
         <summary>Gets search paths for files, directories for temporary files, application-specific options, and other similar information.</summary>
-        <value>A string dictionary that provides environment variables that apply to this process and child processes. The default is <see langword="null" />.</value>
+        <value>A string dictionary that provides environment variables that apply to this process and child processes.</value>
         <remarks>
           <format type="text/markdown"><![CDATA[