Update readme learn more link
If you upload a readme.txt or readme.md file at the root level in your
resource, it will be rendered automatically on the page. Markdown
formatting is allowed in readme.md.<br><strong><a
- href="https://guides.github.com/features/mastering-markdown/#syntax"
+ href="https://daringfireball.net/projects/markdown/basics"
target="_blank">Learn more about Markdown</a></strong>
</em>
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