lint: skip MD029 and MD036

Skipping:

* MD029 Ordered list item prefix
* MD036 Emphasis used instead of a header

These rules are not fully applied to this repository yet and
further discussion is probably needed on how to deal with them.

Example markdownlint run:

* https://github.com/Anduin2017/HowToCook/runs/5226805159

.github/workflows/ci.yml

@@ -14,4 +14,4 @@ jobs:
       - name: Install packages
         run: sudo gem install mdl
       - name: Lint markdown files
-        run: mdl *.md
+        run: mdl *.md -r ~MD029,~MD036