Add Description for some source file

cpp/cfgfile.cpp

@@ -1,3 +1,8 @@
+//A Test to read Config files
+// The Config File Should be a text file 
+// and the content as follows
+// key=value
+
 #include <iostream>
 #include <fstream>
 #include <string>

cpp/m4s_to_mp4.cpp

@@ -1,3 +1,6 @@
+//This tool is to automatically execute ffmpeg
+//Use audio.m4s and video.m4s file to generate a .mp4 file.
+
 #include <iostream>
 #include <cstdio>
 #include <thread>