Add docs for ZonderGas integration (#31229)

source/_integrations/zondergas.markdown

@@ -0,0 +1,20 @@
+---
+title: ZonderGas
+description: Get the energy market prices from ZonderGas using the EnergyZero integration.
+ha_category:
+  - Energy
+  - Sensor
+ha_domain: zondergas
+ha_release: 2024.3
+ha_integration_type: virtual
+ha_supporting_domain: energyzero
+ha_supporting_integration: energyzero
+ha_codeowners:
+  - '@klaasnicolaas'
+ha_config_flow: true
+ha_platforms:
+  - sensor
+ha_iot_class: Cloud Polling
+---
+
+{% include integrations/supported_brand.md %}