diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 333e80b..1a7e037 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -12,3 +12,11 @@ From the repository root directory:
 ```sh
 source src/sh/pre-commit.sh
 ```
+
+See the `cfg/` directory for assorted formatter and linter configurations.
+
+### GitHub actions
+
+This repository uses [GitHub actions](https://docs.github.com/en/actions) to perform
+assorted status checks. For example if you submit a pull request but do not run
+[`pre-commit`](#pre-commit) then your pull request might get blocked.
diff --git a/cfg/markdownlint-config.yaml b/cfg/markdownlint-config.yaml
new file mode 100644
index 0000000..1a85786
--- /dev/null
+++ b/cfg/markdownlint-config.yaml
@@ -0,0 +1,3 @@
+MD013:
+  strict: true
+default: true
diff --git a/cfg/pre-commit-config.yaml b/cfg/pre-commit-config.yaml
index 740d1af..0c5a736 100644
--- a/cfg/pre-commit-config.yaml
+++ b/cfg/pre-commit-config.yaml
@@ -16,7 +16,11 @@ repos:
   rev: '0.7.17'
 -
   hooks:
-  - id: 'markdownlint-fix'
+  -
+    args:
+    - '--config'
+    - 'cfg/markdownlint-config.yaml'
+    id: 'markdownlint-fix'
   repo: 'https://github.com/igorshubovych/markdownlint-cli'
   rev: 'v0.39.0'
 -
diff --git a/cfg/yamllint-config.yaml b/cfg/yamllint-config.yaml
index f0b47ec..0373a72 100644
--- a/cfg/yamllint-config.yaml
+++ b/cfg/yamllint-config.yaml
@@ -1,4 +1,3 @@
-# Used by pre-commit.
 extends: 'default'
 rules:
   braces: