diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 3b204a4..4659081 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -12,6 +12,12 @@ repos:
       - id: end-of-file-fixer
       - id: check-yaml
       - id: check-added-large-files
+  - repo: https://github.com/markdownlint/markdownlint
+    rev: v0.11.0
+    hooks:
+      - id: markdownlint
+        args:
+          - -r "~MD013"                   # ignore line-length rule
   - repo: https://github.com/ansible-community/ansible-lint
     rev: v6.0.2
     hooks:
diff --git a/README.md b/README.md
index d66fb26..9aae7a6 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,6 @@ This repository is not open for contributions, but I might accept suggestions. P
 
 - [myshittycode.com]
 
-
 [LICENSE]: LICENSE
 
 [myshittycode.com]: https://myshittycode.com/
diff --git a/knowledge base/mdl.md b/knowledge base/mdl.md
index 4d6d387..933a84e 100644
--- a/knowledge base/mdl.md	
+++ b/knowledge base/mdl.md	
@@ -11,6 +11,9 @@ gem install mdl
 # Check files.
 mdl README.md
 mdl path/to/dir/
+
+# Ignore a specific rule.
+mdl -r "~MD013" README.md
 ```
 
 ## Further readings
diff --git a/knowledge base/pre-commit.md b/knowledge base/pre-commit.md
index 164e2d0..879914b 100644
--- a/knowledge base/pre-commit.md	
+++ b/knowledge base/pre-commit.md	
@@ -7,8 +7,8 @@
 pre-commit sample-config > .pre-commit-config.yaml
 
 # manually run checks
-pre-commit run --all-files    # all checks
-pre-commit run ansible-lint   # ansible-lint only
+pre-commit run --all-files
+pre-commit run ansible-lint --files ansible/
 
 # automatically run checks at every commit
 pre-commit install
@@ -20,6 +20,34 @@ pre-commit autoupdate
 SKIP=flake8 git commit -m "foo"
 ```
 
+```yaml
+---
+# File .pre-commit-config.yaml
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.2.0
+    hooks:
+      - id: trailing-whitespace
+        args:
+          - --markdown-linebreak-ext=md   # ignore markdown's line break
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-added-large-files
+  - repo: https://github.com/markdownlint/markdownlint
+    rev: v0.11.0
+    hooks:
+      - id: markdownlint
+        args:
+          - -r "~MD013"                   # ignore line-length rule
+  - repo: https://github.com/ansible-community/ansible-lint
+    rev: v6.0.2
+    hooks:
+      - id: ansible-lint
+```
+
 ## Further readings
 
 - Pre-commit's [website]