chore: simplify lint.yml - use centralized validation workflow

Author: CybotTM

.github/workflows/lint.yml

@@ -9,13 +9,6 @@ permissions:
   contents: read
 
 jobs:
-  markdown:
-    name: Markdown
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-      - uses: DavidAnson/markdownlint-cli2-action@07035fd053f7be764496c0f8d8f9f41f98305101 # v22.0.0
-
   validate:
     name: Skill Validation
     uses: netresearch/skill-repo-skill/.github/workflows/validate.yml@main