docker-theia image build tweaks:

- Add slack notification to docker-theia build
- Add a short readme on how to use/run the image

concourse/pipeline.yml

@@ -273,6 +273,11 @@ resources:
 jobs:
 - name: build-theia-docker-snapshot-image
   serial: true
+  on_failure:
+    put: slack-notification
+    params:
+      text: |
+          Concourse ${BUILD_PIPELINE_NAME}/${BUILD_JOB_NAME}/${BUILD_NAME} has failed!
   plan:
   - in_parallel:
     - get: s3-concourse-vsix-snapshot

concourse/theia-docker-image/README.md

@@ -0,0 +1,17 @@
+Theai Docker Image
+==================
+
+We currently plublish a docler image that contains:
+
+- a full-featured `theai` set of package for version `next`.
+- all 4 of our vscode extensions as latest snapshot version.
+
+This image is published to docker hub as `kdvolder/sts4-theia-snapshot:latest`.
+
+You can run it as follows:
+
+```
+docker run -it --init  -p 3000:3000 -p 8080:8080 -v "$(pwd):/home/project:cached" kdvolder/sts4-theia-snapshot:latest
+```
+
+Then open `http://localhost:3000` to access it.