[HUST CSE][document] Fix some comments, invalid grouping commands and warnings in Doxygen.

将Doxygen输入文件（由Doxyfile中的INPUT定义）中的失效Doxygen分组指令（如/*@*/和/*@}*/）更改为有效的分组指令（如/**@*/和/**@}*/）；（此处只对INPUT中的文件做了修改，bsp目录下和libcpu目录下存在近万个失效的Doxygen分组指令，但由于不作为文档的输入文件且这些文件过于庞大老旧，没有对这些文件中的无效指令做修改）
将图片文件统一放入了images目录下；
修改了Doxyfile和部分Doxygen注释，使得Doxyfile能够定位到新的代码路径且不受重复实现的影响；
解决了一些注释中的参数名不匹配、参数多余/缺失等问题。

documentation/doxygen/systeminit.h

@@ -7,7 +7,7 @@
  *
  * @brief System initialization procedure.
  *
- * When RT-Thread operating system starts up, the basic operating system facility 
+ * When RT-Thread operating system starts up, the basic operating system facility
  * initialization routines must be invoked.
  *
  * The suggested initialization sequence is:
@@ -55,19 +55,9 @@
  * has not started. User can allocate memory, create thread, semaphore etc. However,
  * user shall not suspend 'current' thread.
  */
-void rt_application_init()
-{
-}
+void rt_application_init();
 
 /**
  * @ingroup SystemInit
- *
- * This function will initialize system heap memory.
- *
- * @param begin_addr the beginning address of system heap memory.
- * @param end_addr the end address of system heap memory.
- *
  */
-void rt_system_heap_init(void* begin_addr, void* end_addr)
-{
-}
+void rt_system_heap_init(void* begin_addr, void* end_addr);