[FL-1906] Documentation: add Doxyfile, prepare sources for doxygen. (#741)

* Documentation: add Doxyfile, prepare sources for doxygen.

* Update ReadMe and remove obsolete CLA

* Add contribution guide

* Contributing: update text

* Correct spelling

applications/gui/view_i.h

@@ -1,3 +1,8 @@
+/**
+ * @file view_i.h
+ * GUI: internal View API
+ */
+
 #pragma once
 
 #include "view.h"
@@ -26,26 +31,26 @@ struct View {
     void* context;
 };
 
-/* IconAnimation tie callback */
+/** IconAnimation tie callback */
 void view_icon_animation_callback(IconAnimation* instance, void* context);
 
-/* Unlock model */
+/** Unlock model */
 void view_unlock_model(View* view);
 
-/* Draw Callback for View dispatcher */
+/** Draw Callback for View dispatcher */
 void view_draw(View* view, Canvas* canvas);
 
-/* Input Callback for View dispatcher */
+/** Input Callback for View dispatcher */
 bool view_input(View* view, InputEvent* event);
 
-/* Custom Callback for View dispatcher */
+/** Custom Callback for View dispatcher */
 bool view_custom(View* view, uint32_t event);
 
-/* Previous Callback for View dispatcher */
+/** Previous Callback for View dispatcher */
 uint32_t view_previous(View* view);
 
-/* Enter Callback for View dispatcher */
+/** Enter Callback for View dispatcher */
 void view_enter(View* view);
 
-/* Exit Callback for View dispatcher */
+/** Exit Callback for View dispatcher */
 void view_exit(View* view);