Add human friendly name for project_key

In UI, project_key is called 'project name suffix'

config/locales/en.yml

@@ -20,6 +20,8 @@ en:
         token: "Grafana HTTP API Token"
         grafana_url: "Grafana API URL"
         grafana_enabled: "Grafana integration enabled"
+      service_desk_setting:
+        project_key: "Project name suffix"
       user/user_detail:
         job_title: 'Job title'
       user/user_detail: