Add markdown format support (#25)

Co-authored-by: Dawid Dziurla <dawidd0811@gmail.com>

node_modules/showdown/.eslintrc.json

@@ -0,0 +1,27 @@
+{
+  "rules": {
+    "indent": [2, 2, {"SwitchCase": 1, "VariableDeclarator": 2}],
+    "curly": [2, "all"],
+    "operator-linebreak": [2, "after"],
+    "camelcase": [2, {"properties": "never"}],
+    "quotes": [2, "single"],
+    "no-multi-str": 2,
+    "no-mixed-spaces-and-tabs": 2,
+    "no-trailing-spaces": 2,
+    "space-unary-ops": [2,
+      {
+        "nonwords": false,
+        "overrides": {}
+      }
+    ],
+    "brace-style": [2, "1tbs", {"allowSingleLine": true}],
+    "keyword-spacing": [2, {}],
+    "space-infix-ops": 2,
+    "space-before-blocks": [2, "always"],
+    "eol-last": 2,
+    "space-before-function-paren": [2, "always"],
+    "array-bracket-spacing": [2, "never", {"singleValue": false}],
+    "space-in-parens": [2, "never"],
+    "no-multiple-empty-lines": 2
+  }
+}