fix link format (#3327)

Author: mairaw

xml/System/Environment.xml

@@ -997,7 +997,7 @@ On MacOS and Linux, the `GetEnvironmentVariables` method retrieves the name and
         <Parameter Name="target" Type="System.EnvironmentVariableTarget" Index="0" FrameworkAlternate="netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0;netframework-2.0;netframework-3.0;netframework-3.5;netframework-4.0;netframework-4.5;netframework-4.5.1;netframework-4.5.2;netframework-4.6;netframework-4.6.1;netframework-4.6.2;netframework-4.7;netframework-4.7.1;netframework-4.7.2;netframework-4.8;netstandard-2.0;xamarinandroid-7.1;xamarinios-10.8;xamarinmac-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="target">One of the <see cref="T:System.EnvironmentVariableTarget" /> values. Only <see cxref="F:System.EnvironmentVariableTarget.Process" /> is supported on .NET Core running on Unix-based systems. </param>
+        <param name="target">One of the <see cref="T:System.EnvironmentVariableTarget" /> values. Only <see cref="F:System.EnvironmentVariableTarget.Process" /> is supported on .NET Core running on Unix-based systems. </param>
         <summary>Retrieves all environment variable names and their values from the current process, or from the Windows operating system registry key for the current user or local machine.</summary>
         <returns>A dictionary that contains all environment variable names and their values from the source specified by the <paramref name="target" /> parameter; otherwise, an empty dictionary if no environment variables are found.</returns>
         <remarks>