README.md in fluent-plugin-geoip-0.1.0 vs README.md in fluent-plugin-geoip-0.1.1

@@ -162,18 +162,18 @@
 
 ## Placeholders
 
 Provides these placeholders for adding field of geolocate results.
 
-* ${city}
-* ${latitude}
-* ${longitude}
-* ${country_code3}
-* ${country_code}
-* ${country_name}
-* ${dma_code}
-* ${area_code}
-* ${region}
+* ${city[lookup_field]}
+* ${latitude[lookup_field]}
+* ${longitude[lookup_field]}
+* ${country_code3[lookup_field]}
+* ${country_code[lookup_field]}
+* ${country_name[lookup_field]}
+* ${dma_code[lookup_field]}
+* ${area_code[lookup_field]}
+* ${region[lookup_field]}
 
 ## Parameters
 
 * `include_tag_key` (default: false)
 * `tag_key`