add comment explaining the thing

Author: kentcdodds

.github/workflows/validate.yml

@@ -29,6 +29,7 @@ jobs:
         run: |
           npx --yes epicshop@latest add ${{ github.event.repository.name }} ./workshop
         env:
+          # Kept getting npm ECOMPROMISED errors on windows. This fixed it.
           npm_config_cache: ${{ runner.temp }}/npm-cache
 
       - name: ʦ TypeScript