Add README with info on tests

Author: carreter

e2e/README.md

@@ -0,0 +1,23 @@
+# End-to-end tests for konnectivity-network-proxy running in a KinD cluster
+
+These e2e tests deploy the KNP agent and server to a local [KinD](https://kind.sigs.k8s.io/)
+cluster to verify their functionality.
+
+These can be run automatically using `make e2e-test`.
+
+## Setup in `main_test.go`
+
+Before any of the actual tests are run, the `TestMain()` function
+in `main_test.go` performs the following set up steps:
+
+- Spin up a new KinD cluster with the node image provided by the `-kind-image` flag.
+- Sideload the KNP agent and server images provided with `-agent-image` and `-server-image` into the cluster.
+- Deploy the necessary RBAC and service templates for both the KNP agent and server (see `renderAndApplyManifests`).
+
+## The tests
+
+### `static_count_test.go`
+
+These tests deploy the KNP servers and agents to the previously created KinD cluster.
+After the deployments are up, the tests check that both the agent and server report
+the correct number of connections on their metrics endpoints.