Add short explanation for has_core_infrastructures_badge to readme

[florian-huber]

I just re-ran howfairis on https://github.com/matchms/ms2deepscore
... and then found that to me (no software development background) the message x has_core_infrastructures_badge is not a very clear pointer. I was thinking of tools such as Sonarcloud or Codacy, but I am not sure. Maybe it would be good to mention examples in the readme?

By the way: Should Sonarcloud count for this, than it apparently wasn't able to read the batches on the ms2deepscore github.