Bug#1020595: ITP: tomlplusplus -- TOML config parser and serializer for C++17

[Andrea Pappacoda <andrea@pappacoda.it>]

Hi Stephan, I've uploaded the package to Mentors. I still haven't 
package Poxy, but in the meantime I've included the partial Markdown 
documentation. I'll add the rest in a future revision of the package.

When uploading the package, could you also transfer 
<https://salsa.debian.org/tachi/tomlplusplus> to the debian namespace? 
The transfer button is under Settings -> General -> Advanced -> 
Transfer project