Cleanup Edit with GitHub

Summary:
- Now using a table layout. While having the link inside of the header worked well in the browser, the search API would put "Edit in GitHub" as part of the title -_-
- Instead of putting the link inside of every section like Props, put it on the page header. This makes it less repetetitive and also works on API pages where the link was absent before
- Remove "Run this example" link as there's a giant Run this example sidebar already.
Closes https://github.com/facebook/react-native/pull/5643

Reviewed By: svcscm

Differential Revision: D2883989

Pulled By: vjeux

fb-gh-sync-id: e810e1677d5130692997dd301d6d59cfe04b948f

website/server/extractDocs.js

@@ -137,6 +137,7 @@ function componentsToMarkdown(type, json, filepath, i, styles) {
     'next: ' + next,
     'sidebar: ' + shouldDisplayInSidebar(componentName),
     'runnable:' + isRunnable(componentName),
+    'path:' + json.filepath,
     '---',
     JSON.stringify(json, null, 2),
   ].filter(function(line) { return line; }).join('\n');