Clarify background step schema and error messages

Author: lokesh755

workflow-parser/src/model/converter/steps.ts

@@ -167,7 +167,7 @@ function convertStep(context: TemplateContext, idBuilder: IdBuilder, step: Templ
       cancel
     };
   }
-  context.error(step, "Expected uses or run to be defined");
+  context.error(step, "Expected one of uses, run, wait, wait-all, or cancel to be defined");
 }
 
 function createActionStepId(step: ActionStep): string {

workflow-parser/src/workflow-v1.0.json

@@ -2132,7 +2132,7 @@
       }
     },
     "steps": {
-      "description": "A job contains a sequence of tasks called `steps`. Steps can run commands, run setup tasks, or run an action in your repository, a public repository, or an action published in a Docker registry. Not all steps run actions, but all actions run as a step. Each step runs in its own process in the runner environment and has access to the workspace and filesystem. Because steps run in their own process, changes to environment variables are not preserved between steps. GitHub provides built-in steps to set up and complete a job. Must contain either `uses` or `run`.",
+      "description": "A job contains a sequence of tasks called `steps`. Steps can run commands, run setup tasks, run an action in your repository, a public repository, or an action published in a Docker registry, wait for background steps to complete, or cancel a background step. Not all steps run actions, but all actions run as a step. Each step runs in its own process in the runner environment and has access to the workspace and filesystem. Because steps run in their own process, changes to environment variables are not preserved between steps. GitHub provides built-in steps to set up and complete a job.",
       "sequence": {
         "item-type": "steps-item"
       }