Add markdown format support (#25)

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

node_modules/showdown/test/cases/github-style-codeblock.md

@@ -0,0 +1,34 @@
+
+Define a function in javascript:
+
+```
+function MyFunc(a) {
+    var s = '`';
+}
+```
+
+And some HTML
+
+```html
+<div>HTML!</div>
+```
+
+And some CSS with spaces before the language declaration
+
+```    css
+body {
+    font-size: 1.5em;
+}
+```
+
+Use more than 3 backticks
+
+`````
+some code
+`````
+
+Use tilde as delimiter
+
+~~~
+another piece of code
+~~~