=== Use values from environment vriables

The command line option `-i` can be used to inject environment variables.

e.g
```sh
yamlfu test.yaml -e NAME
```

[cols="1a,1a", options="header"]
.Extra YAML example
|===
|YAMLFu|YAML|
.test.yaml
[source, yaml]
....
JOB NAME: '{NAME}'
....
|
.export NAME="Boat" && yamlfu test.yaml -e NAME
[source, yaml]
....
JOB NAME: Boat
....
|===
