Can I create .config file and include it to web.config? How can i do this?
UPD. If you want to separate config file, for example, move appSettings to another file you must do next: In web.config
<appSettings configSource="myAppSettings.config" />
In myAppSettings.config:
<appSettings>
<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />
</appSettings>