Typo in cache updater

.github/workflows/cache-update.yml

@@ -4,8 +4,15 @@ on:
   schedule:
     - cron: '*/30 * * * *' # every 30m for testing
 
+# A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:
-    # Cache location for arm tools
+  # This workflow contains a single job called "build"
+  build:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-latest
+
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:    # Cache location for arm tools
     - name: Cache arm-none-eabi-gcc tools
       id: cache-arm-gcc
       uses: actions/cache@v1