doc: add Doxygen build system

- add Doxygen build configuration file template and CMake list file.
- add option for building documentation.
- the content of documentation should be filled in future.

doc/src/index.dox

@@ -0,0 +1,10 @@
+/**
+
+\mainpage YYCCommonplace Library Manual
+
+This manual is organized into the following chapters and appendices:
+
+\subpage intro
+
+
+*/

doc/src/intro.dox

@@ -0,0 +1,11 @@
+/**
+
+\page intro Introduction to YYCCommonplace
+
+work in progress
+
+\section work in progress
+
+work in progress
+
+*/