Update _index.md

Rename --from-file to --from-env-file for Command `using env file`

Author: kodePhile

site/content/en/references/kubectl/create/configMap/_index.md

@@ -88,7 +88,7 @@ SAMPLER_PARAMETERS=0.1
 ### Command
 
 ```bash
-kubectl create configmap my-config --from-file=tracing.env
+kubectl create configmap my-config --from-env-file=tracing.env
 ```
 
 ### Output
@@ -98,4 +98,4 @@ $ kubectl get configmap
 
 NAME DATA AGE
 my-config 1 21s
-```
+```