Fix a single tiny typo (#38)

Author: stakx

src/NuGet.Server/Web.config

@@ -52,7 +52,7 @@
     <add key="enableFrameworkFiltering" value="false" />
 
     <!--
-    When running NuGet.Server in a NAT network, ASP.NET may embed the erver's internal IP address in the V2 feed.
+    When running NuGet.Server in a NAT network, ASP.NET may embed the server's internal IP address in the V2 feed.
     Uncomment the following configuration entry to enable NAT support.
     -->
     <!-- <add key="aspnet:UseHostHeaderForRequestUrl" value="true" /> -->