Add markdown story

Author: garronej

stories/Markdown.stories.tsx

@@ -0,0 +1,20 @@
+import { Markdown } from "../docs/Markdown";
+import { sectionName } from "./sectionName";
+import { getStoryFactory } from "./getStory";
+
+const { meta, getStory } = getStoryFactory({
+    sectionName,
+    "wrappedComponent": { Markdown }
+});
+
+export default meta;
+
+export const Default = getStory({
+    "children": `
+\`\`\`diff
++ A line added
+- A line removed
+A line that hasn't moved
+\`\`\`
+`
+});