docs: add documentation for generic ci systems

docs/deployment/continuous-integration/generic.md

@@ -0,0 +1,25 @@
+# Generic CI/CD Integration
+
+In cases where there is no direct or documented integration available, the Dokku project provides an [Official Docker Image](https://github.com/dokku/ci-docker-image) for use in Continuous Integration/Continuous Deployment (CI/CD) systems.
+
+Assuming a Docker image can be run as a CI task with environment variables injected, the following CI systems will have their variables automatically detected:
+
+- [circleci](https://circleci.com/)
+- [cloudbees](https://www.cloudbees.com/)
+- [drone](https://www.drone.io/)
+- [github actions](https://github.com/features/actions)
+- [gitlab-ci](https://about.gitlab.com/stages-devops-lifecycle/continuous-integration/)
+- [semaphoreci](https://semaphoreci.com/)
+- [travisci](https://travis-ci.com/)
+
+## Simple Usage
+
+The simplest usage of the image is as follows.
+
+```shell
+# where the `.env` file contains `GIT_REMOTE_URL` and `SSH_PRIVATE_KEY`
+
+docker run --rm -v="$PWD:/app" --env-file=.env dokku/ci-docker-image dokku-deploy
+```
+
+For more configuration examples and further documentation, see the [ci-docker-image](https://github.com/dokku/ci-docker-image) readme.

docs/template.html

@@ -178,6 +178,7 @@
             <a href="#" class="list-group-item disabled">Continuous Integration</a>
             <a href="/{{NAME}}/deployment/continuous-integration/github-actions/" class="list-group-item">Github Actions</a>
             <a href="/{{NAME}}/deployment/continuous-integration/gitlab-ci/" class="list-group-item">Gitlab CI</a>
+            <a href="/{{NAME}}/deployment/continuous-integration/generic/" class="list-group-item">Generic</a>
 
             <a href="#" class="list-group-item disabled">Community Contributions</a>
             <a href="/{{NAME}}/community/clients/" class="list-group-item">Clients</a>