Update 03.create_app_04.md

Replaced maverick to wrangler

Author: Jawon Song

docs/03.create_app_04.md

@@ -72,7 +72,7 @@ Registering deploy-username-app.json as a TACC.cloud app
 Successfully added app username-fastqc-0.11.7
 | id                     | executionSystem            | revision | isPublic | lastModified|
 | --                     | ---------------            | -------- | -------- | ------------|
-| username-fastqc-0.11.7 | hpc-tacc-maverick-username | 1        | false    | Apr 26, 2018 7:38 pm|
+| username-fastqc-0.11.7 | hpc-tacc-wrangler-username | 1        | false    | Apr 26, 2018 7:38 pm|
 apps-deploy has run to completion.
 ```