Improve documentation workflow (#163)

* Compact project relative paths from doc directory

* Remove committed example_list.md

- generate example_list from cmake for documentation

* Fix doxygen same-line comments

* Add workflow for generating documentation

examples/dom/package_manager.cpp

@@ -14,8 +14,6 @@
 #include "ftxui/screen/box.hpp"
 #include "ftxui/screen/color.hpp"
 
-/// @example examples/dom/package_manage.cpp
-
 int main(int argc, const char* argv[]) {
   using namespace ftxui;