[TASK] Add info for self-hosted runners

.gitlab-ci.yml

@@ -1,5 +1,8 @@
+stages:
+  - ddev-stage
+
 ddev-initialize:
-  stage: project-template-test
+  stage: ddev-stage
   image: ghcr.io/ochorocho/ddev-gitlab-ci:v1.23
   variables:
     # Remove "umask 0000" usage, so DDEV has permissions on the cloned repository
@@ -9,5 +12,7 @@ ddev-initialize:
     - name: docker:dind
   when: always
   script:
+    # Fix for: Error response from daemon: invalid mount config for type "bind": bind source path does not exist: /builds/*/*'
+    - ddev config global --no-bind-mounts=true
     - ddev --version
     # ... do things

README.md

@@ -1,10 +1,29 @@
 # DDEV GitLab CI - Docker in Docker (dind)
 
 This image is most likely to be used within the GitLab Runner.
-As of now it only tested it on gitlab.com
+As of now it is only tested on gitlab.com
 
 **GitLab CI example**: [.gitlab-ci.yml](.gitlab-ci.yml)
 
+## Configuration for self-hosted GitLab Runners
+
+:warning: This (section) information is "work in progress"
+
+```toml
+# ...
+
+[[runners]]
+  # ...
+  [runners.docker]
+    # ...
+    # Could be a security issues: https://docs.gitlab.com/runner/security/#usage-of-docker-executor
+    privileged = true
+    volumes = ["gitlab-shared-cache:/cache", "/var/run/docker.sock:/var/run/docker.sock"]
+    # Add additional groups the container process will run as.
+    # See https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runnersdocker-section
+    group_add = ["999"]
+```
+
 # Workflow - Image build
 
 Build the image