Added badges to the package README, and the Uploads coverage job to t…

…he unit tests workflow. (opensearch-project#104)

* Added badges to the package README, and the Uploads coverage job to the unit tests workflow.

* Removing code coverage upload token.

.github/workflows/unit-tests-workflow.yml

@@ -45,4 +45,6 @@ jobs:
       - name: Run tests
         run: |
           cd OpenSearch-Dashboards/plugins/alerting-dashboards-plugin
-          yarn run test:jest
+          yarn run test:jest --coverage
+      - name: Uploads coverage
+        uses: codecov/codecov-action@v1

README.md

@@ -1,3 +1,10 @@
+[![Unit tests](https://github.com/opensearch-project/alerting-dashboards-plugin/workflows/Unit%20tests%20workflow/badge.svg)](https://github.com/opensearch-project/alerting-dashboards-plugin/actions?query=workflow%3A%22Unit+tests+workflow%22)
+[![Integration tests](https://github.com/opensearch-project/alerting-dashboards-plugin/workflows/E2E%20Cypress%20tests/badge.svg)](https://github.com/opensearch-project/alerting-dashboards-plugin/actions?query=workflow%3A%22E2E+Cypress+tests%22)
+[![codecov](https://codecov.io/gh/opensearch-project/alerting-dashboards-plugin/branch/main/graph/badge.svg)](https://codecov.io/gh/opensearch-project/alerting-dashboards-plugin)
+[![Documentation](https://img.shields.io/badge/doc-reference-blue)](https://opensearch.org/docs/monitoring-plugins/alerting/index/)
+[![Forum](https://img.shields.io/badge/chat-on%20forums-blue)](https://discuss.opendistrocommunity.dev/c/Use-this-category-for-all-questions-around-machine-learning-plugins)
+![PRs welcome!](https://img.shields.io/badge/PRs-welcome!-success)
+
 <img src="https://opensearch.org/assets/brand/SVG/Logo/opensearch_logo_default.svg" height="64px"/>
 
 - [OpenSearch Alerting Dashboards](#opensearch-alerting-dashboards)