message: Update README build, CMake sections
diff: @@ -95,6 +95,7 @@ for a list of available options or read the
  ```sh
  ./configure
  +cd build
  make
  make test
  make install [as root, optional]
  @@ -105,7 +106,12 @@ make install [as root, optional]
  All available CMake variables are available
  [online](https://github.com/actor-framework/actor-framework/wiki/CMake-Options).
  CAF also can be included as CMake submodule or added as dependency to other
  -CMake-based projects using the file `cmake/FindCAF.cmake`.
  +CMake-based projects. The latter can be achieved by calling
  +```cmake
  +find_package(CAF REQUIRED)
  +```
  +in respective project's CMake file. CAF's install location (e.g. by providing
  +the `CMAKE_PREFIX_PATH` option) has to be known.
  ### Using SNocs
  