Wiki preview only supports markdown
In the page editor for wiki pages we only support previews for markdown, but we always show the 'preview' button. Either we need to support previews for all supported formats, or we need to hide the preview button when it is not appropriate.
Steps to reproduce
Set the page format to something other than markdown, and try to use the preview button.
What is the current bug behavior?
The preview button is shown, but when pressed it only shows the original source.
What is the expected correct behavior?
- no render preview button is shown when the format is not markdown
- user can preview their document, no matter what format it is.
Hide the preview button if the current wiki format is not markdown.