diff --git a/.examples/proxy/docker-compose.proxy-example.yml b/.examples/proxy/docker-compose.proxy-example.yml
index 31f2747..bdc0c80 100644
--- a/.examples/proxy/docker-compose.proxy-example.yml
+++ b/.examples/proxy/docker-compose.proxy-example.yml
@@ -1,6 +1,7 @@
-version: '2'
-services:
+---
+version: "2"
 
+services:
   zammad-nginx:
     environment:
       - VIRTUAL_HOST=helpdesk.domain.tld
diff --git a/.examples/proxy/docker-compose.yml b/.examples/proxy/docker-compose.yml
index fad2dea..e2b2e1c 100644
--- a/.examples/proxy/docker-compose.yml
+++ b/.examples/proxy/docker-compose.yml
@@ -1,4 +1,6 @@
+---
 version: '2'
+
 services:
   frontend:
     image: jwilder/nginx-proxy:alpine
@@ -10,7 +12,7 @@ services:
       - ./certs:/etc/nginx/certs
       - /var/run/docker.sock:/tmp/docker.sock:ro
     networks:
-    - 2_apps
+      - 2_apps
 
 networks:
   2_apps:
diff --git a/.github/linters/.markdown-lint.yml b/.github/linters/.markdown-lint.yml
index 5d7892a..a3777d6 100644
--- a/.github/linters/.markdown-lint.yml
+++ b/.github/linters/.markdown-lint.yml
@@ -1,2 +1,3 @@
+---
 MD013:
-  line_length: 500
+  line_length: 600
diff --git a/.github/workflows/ci-remote-image.yaml b/.github/workflows/ci-remote-image.yaml
index 9ed0dc4..39e73e8 100644
--- a/.github/workflows/ci-remote-image.yaml
+++ b/.github/workflows/ci-remote-image.yaml
@@ -1,3 +1,4 @@
+---
 name: ci-remote-image
 
 on:
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 7c6b416..662e4f0 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -1,3 +1,4 @@
+---
 name: ci
 
 on:
@@ -38,9 +39,10 @@ jobs:
         env:
           DEFAULT_BRANCH: master
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          LINTER_RULES_PATH: .github/linters
+          # VALIDATE_ALL_CODEBASE: false
           VALIDATE_JSCPD: false
 
-
   build-and-run-docker-compose:
     needs:
       - codespell
diff --git a/docker-compose.override-local.yml b/docker-compose.override-local.yml
index 14baddf..f10bab4 100644
--- a/docker-compose.override-local.yml
+++ b/docker-compose.override-local.yml
@@ -1,3 +1,4 @@
+---
 version: '3'
 
 services:
diff --git a/docker-compose.override.yml b/docker-compose.override.yml
index f7888bb..3c1e74f 100644
--- a/docker-compose.override.yml
+++ b/docker-compose.override.yml
@@ -1,4 +1,6 @@
+---
 version: '3'
+
 services:
 
   zammad-nginx:
diff --git a/docker-compose.yml b/docker-compose.yml
index 621c6f9..1bb3692 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,3 +1,4 @@
+---
 version: '3'
 
 services:
diff --git a/rancher-compose.yml b/rancher-compose.yml
index bc49675..26e6fb3 100644
--- a/rancher-compose.yml
+++ b/rancher-compose.yml
@@ -1,3 +1,4 @@
+---
 version: '2'
 
 services: