Update _episodes/21-1st-workflow.md

Co-Authored-By: Michael R. Crusoe <1330696+mr-c@users.noreply.github.com>

Author: emannuelOC

_episodes/21-1st-workflow.md

@@ -27,7 +27,7 @@ compiles it.
 > <a href="https://view.commonwl.org/workflows/github.com/common-workflow-language/user_guide/blob/gh-pages/_includes/cwl/21-1st-workflow/1st-workflow.cwl"><img src="https://view.commonwl.org/graph/svg/github.com/common-workflow-language/user_guide/blob/gh-pages/_includes/cwl/21-1st-workflow/1st-workflow.cwl" alt="Visualization of 1st-workflow.cwl" /></a>
 {: .callout}
 
-Use a yaml or a JSON object in a separate file to describe the input of a run:
+Use a YAML or a JSON object in a separate file to describe the input of a run:
 
 *1st-workflow-job.yml*