docs: Add details on how to run e2e tests

Author: jimmidyson

docs/content/contributing/_index.md

@@ -0,0 +1,5 @@
++++
+title = "Contributing"
+weight = 99
+icon = "fa-solid fa-gift"
++++

docs/content/contributing/e2e_tests.md

@@ -0,0 +1,49 @@
++++
+title = "End-to-end tests"
++++
+
+This project uses [Ginkgo] to run end-to-end tests. Tests are labelled to make running targeted or specific tests
+easier.
+
+To determine what labels are available, run:
+
+```shell
+ginkgo --dry-run -v -tags e2e ./test/e2e
+```
+
+Tests are currently labelled via infrastructure provider, CNI provider, and addon strategy. Here are some examples to
+specify what tests to run.
+
+Run all AWS tests:
+
+```shell
+make e2e-test E2E_LABEL='provider:AWS'
+```
+
+Run all Cilium tests:
+
+```shell
+make e2e-test E2E_LABEL='cni:Cilium'
+```
+
+Labels can also be combined.
+
+Run Cilium tests on AWS:
+
+```shell
+make e2e-test E2E_LABEL='provider:AWS && cni:Cilium'
+```
+
+To make debugging easier, you can retain the e2e test environment, which by default is cleaned up after tests run:
+
+```shell
+make e2e-test E2E_LABEL='provider:AWS && cni:Cilium' E2E_SKIP_CLEANUP=true
+```
+
+To speed up the development process, if you have only change e2e tests then you can skip rebuilding the whole project:
+
+```shell
+make e2e-test E2E_LABEL='provider:AWS && cni:Cilium' SKIP_BUILD=true
+```
+
+[Ginkgo]: https://onsi.github.io/ginkgo/