Update .codeclimate.yml

This adds ESLint and markdownlint to your analysis. Be sure to check out the docs for each of these plugins if you'd like to tweak their configuration further.

- https://docs.codeclimate.com/docs/markdownlint
https://docs.codeclimate.com/docs/eslint

.codeclimate.yml

@@ -1,4 +1,9 @@
 version: "2"         # required to adjust maintainability checks
+plugins:
+  eslint:
+    enabled: true
+  markdownlint:
+    enabled: true
 checks:
   argument-count:
     config: