Revert examples change + add doc.

examples/component/input.cpp

@@ -4,7 +4,6 @@
 #include <memory>  // for allocator, __shared_ptr_access
 #include <string>  // for char_traits, operator+, string, basic_string
 
-#ifndef FTXUI_BUILD_MODULES
 #include "ftxui/component/captured_mouse.hpp"  // for ftxui
 #include "ftxui/component/component.hpp"       // for Input, Renderer, Vertical
 #include "ftxui/component/component_base.hpp"  // for ComponentBase
@@ -12,11 +11,6 @@
 #include "ftxui/component/screen_interactive.hpp"  // for Component, ScreenInteractive
 #include "ftxui/dom/elements.hpp"  // for text, hbox, separator, Element, operator|, vbox, border
 #include "ftxui/util/ref.hpp"  // for Ref
-#else
-import ftxui.component;
-import ftxui.dom;
-import ftxui.util;
-#endif
 
 int main() {
   using namespace ftxui;