Meta: Invoke markdown-checker if available while linting

Meta/check-markdown.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+set -eo pipefail
+
+script_path=$(cd -P -- "$(dirname -- "$0")" && pwd -P)
+cd "${script_path}/.."
+
+if [ -z "${CHECK_MARKDOWN_BINARY:-}" ] ; then
+    if ! [ -d Build/lagom/ ] ; then
+        echo "Directory Build/lagom/ does not exist. Skipping markdown check."
+        exit 0
+    fi
+    if ! [ -r Build/lagom/markdown-check ] ; then
+        echo "Lagom executable markdown-check was not built. Skipping markdown check."
+        echo "To enable this check, you may need to run './Meta/serenity.sh build lagom' first."
+        exit 0
+    fi
+    CHECK_MARKDOWN_BINARY="Build/lagom/markdown-check"
+fi
+
+find AK Base Documentation Kernel Meta Ports Tests Userland -path 'Ports/*/*' -prune -o -type f -name '*.md' -print0 | xargs -0 "${CHECK_MARKDOWN_BINARY}" README.md

Meta/lint-ci.sh

@@ -22,6 +22,7 @@ set +e
 for cmd in \
         Meta/check-ak-test-files.sh \
         Meta/check-debug-flags.sh \
+        Meta/check-markdown.sh \
         Meta/check-newlines-at-eof.py \
         Meta/check-style.sh \
         Meta/lint-executable-resources.sh \