cppyy/doc enhancements

[b1shtream]

While building the project, I noticed the following points that needs to be addressed in the documentation to avoid any confusions.

• We do not need to create $ mkdir build directory again because it already gets created during the previous steps.

• Local module libcppyy.so exists in root directory of CPyCppyy not in build directory.

[wlav]

Rather, what's missing there is a cd build, then the recipe works. The build directory that is there in the package itself is from wheel and should not be used when using the cmake interface (build files will be different). The idea here is to create a directory (called build or whatever) outside the main package.

[b1shtream]

@wlav Got it. After cd build when running cmake ../CPyCppyy shows the error: /path/CPyCppyy source not found. The command should be cmake ../../CPyCppyy which runs successfully.

[wlav]

No, I still don't quite understand. Structure that I envision is like this:

   <workdir>
          \- CPyCppyy
          \- build

so the CMakeLists.txt file is found in ../CPyCppyy when you're in build.

It all doesn't matter a whole lot, just that since pip creates and uses a build directory in CPyCppyy, all one should care about is that the two directories are disjoint.

Note that the only reason for using cmake to build is that running make (or whatever build system you prefer) is a whole lot faster than using pip in development mode, so it saves time. cmake isn't otherwise used in the distribution/installation.