add comment explaining document status options

.github/workflows/w3c-publish.yml

@@ -5,7 +5,12 @@ on:
     branches: [ main ]
     paths: [ .github/**, document/** ]
 
-  # Allows you to run this workflow manually from the Actions tab
+  # Allows you to run this workflow manually from the Actions tab, gh CLI tool,
+  # or REST API. THe w3c-status options correspond to the valid options for
+  # Bikeshed's --md-status flag, and refer to the W3C rec-track document
+  # stages described in https://www.w3.org/policies/process/#maturity-stages
+  # (Editor's Draft, Working Draft, Candidiate Recommendation Draft, and
+  # Candidate Recommendation Snapshot).
   workflow_dispatch:
     inputs:
       w3c-status: