Docgen: log per vendor.

support/docgen.js

@@ -118,14 +118,20 @@ const logDevices = (devices) => {
     });
 }
 
+const vendors = Array.from(new Set(Object.values(deviceMapping).map((d) => d.vendor)));
+vendors.sort();
+
 console.log('GENERATED')
 console.log('=============================')
 console.log('*NOTE: Automatically generated by `npm run docgen`*')
 console.log('')
 console.log('In case your device is **NOT** listed here, please create an issue at: https://github.com/Koenkk/zigbee2mqtt/issues');
 console.log('')
-logDevices(Object.values(deviceMapping));
-console.log('');
+vendors.forEach((vendor) => {
+    console.log(`### ${vendor}`);
+    logDevices(Object.values(deviceMapping).filter((d) => d.vendor === vendor));
+    console.log('');
+})
 console.log('### Planned to support');
 console.log('Devices listed below are **NOT** supported but are planned to be.');
 console.log('')