Update HostingEnvironmentExtensions.xml

Author: analogrelay

xml/Microsoft.Extensions.Hosting/HostingEnvironmentExtensions.xml

@@ -78,10 +78,13 @@
       <Docs>
         <param name="hostingEnvironment">An instance of <see cref="T:Microsoft.Extensions.Hosting.IHostingEnvironment" />.</param>
         <param name="environmentName">Environment name to validate against.</param>
-        <summary>Compares the current hosting environment name against the specified value.</summary>
+        <summary>Compares the current hosting environment name against the specified value. Library authors should avoid using this API, see remarks for details.</summary>
         <returns>
           <see langword="true" /> if the specified name is the same as the current environment; otherwise, <see langword="false" />.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>
+          Environment names are generally specific to an application. Libraries designed for use in many different applications
+          should avoid coupling behavior to specific environment names.
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="IsProduction">