Adding installation and test notes

[pclausen]

Adding installation and test notes based on the same file from https://github.com/exercism/cpp.git

@kotp : Please check if the git log is sane - I still feel very uncertain about what I am doing with git

[SaschaMann]

I can't seem to split the comments to separate reviews, the requested change only covers the mention of C++, the other change is up to you to decide.

[SaschaMann]

@kotp : Please check if the git log is sane - I still feel very uncertain about what I am doing with git

This is minor, but commit message subject lines should be written in the imperative mood, e.g. Add instead of Adding in this case. It should be able to complete the sentence "If applied, this commit will your subject line here" (see Chris Beams' blog post for a longer explanation).

Imo not worth changing it for this commit now, but something worth keeping in mind for the future.

[kotp]

As you are learning Git, it might be worth mentioning that you could do git commit --amend to change the git commit message if you want to, and then doing a git push -f <remote> <branch> if your workflow is explicit... or git push -f if it is implicit.