FYI - Your https link generates a cert error because node.green is being served with the www.github.com ssl cert.
From what I understand (and I admit, my knowledge is pretty lacking around what cloudflare offers) the free part is only the security between the client and cloudflare (and not the security between cloudflare and your server).
On one hand it's better than nothing as I assume most MITMs are on local wifis and such but on the other it gives users a false sense of security.
Then again none of this is of actual concern for node.green
I made my blog hosted on Github HTTPS with this, mainly so that I can experiment some features like Service Workers.
The free plan also supports securing the connection between CloudFlare and your server.