cmake `target_include_directories` to "export" include directories to a using parent cmake project

[cristiarg]

I used the library to build something and found out that, #include "telebot.h" in my program does not find it.

One way to export telebot's include dir for use in the parent project is this:

# NOTE: this is added to export this project's include directories to the
# outside world for a parent cmake project to reference them
target_include_directories(${PROJECT_NAME} PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include)