Disqus loads it's embed config.js from its root domain (https://disqus.com). Our CSPs only allow subdomains (e.g.: https://codimd.disqus.com). This causes the disqus embedding to fail. This patch should fix this problem by adding https://disqus.com to the CSP setting. From a security perspective there is no real change. Since still the same parties are involved. Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>