chore: bump markdownlint-cli2 in makefile

Author: omissis

Makefile

@@ -13,7 +13,7 @@ _DOCKER_GOLANGCI_LINT_IMAGE=golangci/golangci-lint:v1.64.8
 _DOCKER_HADOLINT_IMAGE=hadolint/hadolint:v2.12.0
 _DOCKER_JSONLINT_IMAGE=cytopia/jsonlint:1.6
 _DOCKER_MAKEFILELINT_IMAGE=cytopia/checkmake:latest-0.5
-_DOCKER_MARKDOWNLINT_IMAGE=davidanson/markdownlint-cli2:v0.14.0
+_DOCKER_MARKDOWNLINT_IMAGE=davidanson/markdownlint-cli2:v0.18.0
 _DOCKER_SHELLCHECK_IMAGE=koalaman/shellcheck-alpine:v0.10.0
 _DOCKER_SHFMT_IMAGE=mvdan/shfmt:v3-alpine
 _DOCKER_TOOLS_IMAGE=omissis/go-jsonschema:tools-latest