Add README to test folder (#2339)

* Add README to test folder

* Kubernetes members can trigger PR tests

test/README.md

@@ -0,0 +1,52 @@
+# Charts Testing
+
+## Pull Request Testing
+
+### Procedure
+
+Pull requests testing is run via the [Kuberentes Test Infrastructure](https://github.com/kubernetes/test-infra).
+
+The configuration of the Pull Request trigger is [in the config.json](https://github.com/kubernetes/test-infra/blob/827797c54b48295045698465b437f463ca9276c2/jobs/config.json#L10285).
+
+This snippet tells Test Infra to run the [test/e2e.sh](https://github.com/kubernetes/charts/blob/master/test/e2e.sh)
+when testing is triggered on a pull request. The e2e.sh script will use the [Charts test image](https://github.com/kubernetes/charts/blob/master/test/Dockerfile)
+to run the [test/changed.sh](https://github.com/kubernetes/charts/blob/master/test/changed.sh) script. This script 
+is the main logic for validation of a pull request. It intends to only test charts that have changed in this PR.
+
+The logic is as follows:
+
+1. [Get credentials for the Kubernetes cluster used for testing.](https://github.com/kubernetes/charts/blob/master/test/changed.sh#L42)
+1. [Install and initialize Helm](https://github.com/kubernetes/charts/blob/master/test/changed.sh#L47)
+1. [For any charts that have changed](https://github.com/kubernetes/charts/blob/master/test/changed.sh#L62):
+    - Download dependent charts, if any, with `helm dep update`
+    - Run `helm lint` on the chart
+    - Run `helm install` in a new namespace for this PR+build
+    - Use the [test/verify-release.sh](https://github.com/kubernetes/charts/blob/master/test/verify-release.sh) to ensure that if any pods were launched that they get to the `Running` state
+    - Run `helm test` on the release
+    - Delete the release
+
+### Triggering
+
+In order for the tests to be kicked off one of the 
+[Kubernetes member](https://github.com/orgs/kubernetes/people) must add the 
+"ok-to-test" label. This can also be done by commenting "/ok-to-test" on the pull request. 
+
+This check is there to ensure that PRs are spot checked for any nefarious code. There are 2 things to check for:
+
+1. No changes have been made to file in the test folder that unnecessarily alter the testing procedures.
+1. The chart is not using images whose provenance is not traceable (usually done via the sources metadata field).
+
+## Repo syncing
+
+The syncing of charts to the stable and incubator repos happens from a Jenkins instance that is polling for changes
+to the master branch. On each change it will use the [test/repo-sync.sh](https://github.com/kubernetes/charts/blob/master/test/repo-sync.sh)
+to update the public repositories. The procedure is as follows:
+
+1. [Setup Helm](https://github.com/kubernetes/charts/blob/master/test/repo-sync.sh#L16)
+1. [Authenticate to Google Cloud so that we can upload to the Cloud Storage bucket that hosts the charts](https://github.com/kubernetes/charts/blob/master/test/repo-sync.sh#L27)
+1. For the stable and incubator folders:
+   - Download the existing index.yaml from the repository
+   - Run `helm dep update` on all the charts in the current repository
+   - Run `helm package` on each chart
+   - Recreate the index using `helm repo index`
+   - Upload the repostory using `gsutil rsync`