markdownlint: ignore checks that will be autofixed by nvim

.markdownlintrc

@@ -6,5 +6,8 @@
     "code_block_line_length": 140,
     "tables": false
   },
+  "MD009": false, // no-trailing-spaces, auto-fixed by formatter/LSP
+  "MD012": false, //no-multiple-blanks, auto-fixed by formatter/LSP
+  "MD032": false, // blanks-around-lists, auto-fixed by formatter/LSP
   "MD046": { "style": "fenced" }
 }