Add more documentation to functions/header files

include/render.h

@@ -5,6 +5,14 @@
 #ifndef _RENDER_H
 #define _RENDER_H
 
+/**
+ * "Renders" the given container (and its children), meaning that all rects are
+ * updated correctly. Note that this function does not call any xcb_*
+ * functions, so the changes are completely done in memory only (and
+ * side-effect free). As soon as you call x_push_changes(), the changes will be
+ * updated in X11.
+ *
+ */
 void render_con(Con *con);
 
 #endif