Workflow upload artifacts and create release fix 2

.github/workflows/workflow.yml

@@ -41,6 +41,6 @@ jobs:
       - name: Create release
         uses: ncipollo/release-action@v1
         with:
-          tag: ${{ github.sha }}
+          tag: main
           commit: main
           artifacts: "*.bin"

README.md

@@ -1,5 +1,7 @@
 # BTClock v2
 
+[![BTClock CI](https://github.com/dsbaars/btclock_v2/actions/workflows/workflow.yml/badge.svg)](https://github.com/dsbaars/btclock_v2/actions/workflows/workflow.yml)
+
 Improved code for BTClock with many features.
 Don't forget to copy `config.h.example` to `config.h`. Not necessary to adapt it, since everything should be configurable through the WebUI.