Docs: Refined syntax highlighting and fixed c++

Docs: Refined syntax highlighting and fixed c++

I specified the language on each relevant code example, so the proper syntax highlighting should be used.

Also I fixed the C++ part, where every angle bracket was escaped with additional quotation marks and thus hiding some relevant information in the online docs.

Also I added a C++ output functionality with `std::setprecision` (from the include `iomanip`) which behaves equivalent to the printf from the C\C++ part.