add screenshots

Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>

appinfo/info.xml

@@ -11,6 +11,9 @@
     <namespace>DataRequest</namespace>
     <category>tools</category>
     <bugs>https://github.com/nextcloud/data_request/issues</bugs>
+    <repository type="git">https://github.com/nextcloud/data_request.git</repository>
+    <screenshot>https://raw.githubusercontent.com/nextcloud/data_request/screenshots/personal-settings.png</screenshot>
+    <screenshot>https://raw.githubusercontent.com/nextcloud/data_request/screenshots/settings-close-up.png</screenshot>
     <dependencies>
         <nextcloud min-version="13" max-version="13"/>
     </dependencies>