Document VAADIN Debug mode in SERVER_DEV_SETUP.md

Author: DavidBaldsiefen

SERVER_DEV_SETUP.md

@@ -1,7 +1,7 @@
 
 
 # Installing a SORMAS Server for development
-**Note: This guide explains how to configure a SORMAS server on Linux and Windows systems for development. Please note that there is no database setup because the script supposes the use of the Docker Postgresql image (see [SORMAS-Docker][https://github.com/hzi-braunschweig/SORMAS-Docker]).**
+**Note: This guide explains how to configure a SORMAS server on Linux and Windows systems for development. Please note that there is no database setup because the script supposes the use of the Docker Postgresql image (see [SORMAS-Docker](https://github.com/hzi-braunschweig/SORMAS-Docker)).**
 
 ## Content
 * [Prerequisites](#prerequisites)
@@ -50,6 +50,10 @@ See [Keycloak](SERVER_SETUP.md#keycloak-server) for how to install Docker locall
 
 If you are doing active development on Keycloak (themes, authentication mechanisms, translations, etc.) it's recommended to install the standalone variant.
 
+## VAADIN Debug Mode
+
+To enable [VAADIN Debug Mode](https://vaadin.com/docs/v8/framework/advanced/advanced-debug.html), go to ``sormas-ui/src/main/webapp/WEB-INF/web.xml`` and ``sormas-rest/src/main/webapp/WEB-INF/web.xml`` and set ``productionMode`` to ``false``.
+Make sure not to commit your changes to these files, for example by using .gitignore.
 
 ## Other components