update README

README.md

-Docker images for GitLab CI
-===========================
+Gitlab Runner for DUNE
+======================
 
 Images
 ------
 
 The current images are:
 
-| image                    | parent            | description                                                |
-|--------------------------|-------------------|------------------------------------------------------------|
-| duneci/base:8            | debian:8          | Debian 8 with gcc 4.9.2, clang 3.5, cmake 3.0.2            |
-| duneci/base:8-backports  | duneci/base:8     | Debian 8 with gcc 4.9.2, clang 3.8 (backport), cmake 3.0.2 |
-| duneci/base:9            | debian:9          | Debian 9 with gcc 6.3, clang 3.8, cmake 3.7                |
-| duneci/base:10           | debian:10         | Debian 9 with gcc 7, clang 4.0, cmake 3.7                  |
-| duneci/base:16.04        | ubuntu:16.04      | Ubuntu LTS 16.04 with gcc 5.4.0, clang 3.8.0, cmake 3.5.1  |
-| duneci/base:18.04        | ubuntu:18.04      | Ubuntu LTS 18.04 with gcc 7.3, clang 6, cmake 3.10.2       |
-| duneci/dune:2.3          | duneci/base:8     | DUNE 2.3 core modules (Debian packages)                    |
-| duneci/dune:2.4          | duneci/base:16.04 | DUNE 2.4 core modules (Debian packages)                    |
-| duneci/dune:2.5          | duneci/base:9     | DUNE 2.5 core and staging modules (Debian packages)        |
-| duneci/dune:2.6          | duneci/base:10    | DUNE 2.6 core and staging modules (Git 2.6 branch)         |
-| duneci/dune:git          | duneci/base:9     | DUNE master core and staging modules (Git)                 |
-| duneci/dune-fufem:2.4    | duneci/dune:2.4   | dune-{fufem,functions,solvers,typetree} (2.4 branch)       |
-| duneci/dune-fufem:git    | duneci/dune:git   | dune-{elasticity,fufem,grid-glue,solvers} (master branch)  |
-
-`.gitlab-ci.yml`
-----------------
-
-Installing dependencies:
-```yaml
-before_script:
-  - duneci-install-module https://gitlab.dune-project.org/core/dune-common.git
-  - duneci-install-module https://gitlab.dune-project.org/core/dune-geometry.git
-```
-
-To build with several images:
-```yaml
----
-dune:2.4--gcc:
-  image: duneci/dune:2.4
-  script: duneci-standard-test
-
-dune:2.4--clang:
-  image: duneci/dune:2.4
-  script: duneci-standard-test --opts=/duneci/opts.clang
-```
-
-You can also specify a default image and use it in several jobs:
-
-```yaml
----
-image: duneci/dune:2.4
-
-dune:2.4--gcc:
-  script: duneci-standard-test
-
-dune:2.4--clang:
-  script: duneci-standard-test --opts=/duneci/opts.clang
-```
-
-For more information, take a look at the [GitLab documentation on `.gitlab-ci.yml`](https://docs.gitlab.com/ce/ci/yaml/README.html).
+| image                    | description                                       |
+|--------------------------|---------------------------------------------------|
+| duneci/docker-builder    | Docker container for building images (privileged) |
+| duneci/proxy             | HTTP proxy server for restricted internet access  |
 
 Updating gitlab-runner
 ----------------------
@@ -66,6 +18,7 @@ To update `gitlab-runner` on the VM:
 
 ```shell
 ./bin/duneci-runner
+./bin/duneci-runner-gc
 ```
 
 The current version can be shown by running