Added Scalingo deployment documentation

[brandon-welsch]

Added documentation for Scalingo one-click deployment

[Yukaii]

@brandon-welsch I see you provide custom branch deployment description in PR hackmdio/codimd#1360, would you like to add them to docs? 🤩

[Yukaii]

And another question for this, which branch will be used for scarlingo deployment? Is the master branch or the default branch set in GitHub repository?

Take our heroku deployment as an example, it's specified to use master branch because we do releases on master branch, but use develop branch as default branch on GitHub.

[brandon-welsch]

@brandon-welsch I see you provide custom branch deployment description in PR hackmdio/codimd#1360, would you like to add them to docs? 🤩

Good point, I will add it thanks.

And another question for this, which branch will be used for scarlingo deployment? Is the master branch or the default branch set in GitHub repository?

Take our heroku deployment as an example, it's specified to use master branch because we do releases on master branch, but use develop branch as default branch on GitHub.

Scalingo deployment uses the master branch in all cases ;), if a branch was not specified

[Yukaii]

Looks good to me now 😍

Just a reminder that we won't put this online until we do our next release :)

Thanks for your contribution @brandon-welsch !

[brandon-welsch]

Thanks to you especially, CodiMD is a tool that I personally love