doc: use doxygen li tags

cpu/x86/include/cpu.h

@@ -71,13 +71,13 @@ static inline void __attribute__((always_inline, noreturn)) x86_hlt(void)
  * @brief   Initialize subsystems and run kernel.
  *
  * Called by the board specific startup code.
- * <li>The .bss has to be cleared before.
- * <li>The stack has to be set up, probably somewhere in the low memory.
- * <li>The A20 line has to be activated, because all the code is beyong 1MB.
- * <li>Paging must be disabled.
- * <li>The SS, DS, and CS must span the whole 4GB of RAM.
- * <li>32 bit protected mode must be entered.
- * <li>Interrupts must be disabled.
+ * @li The .bss has to be cleared before.
+ * @li The stack has to be set up, probably somewhere in the low memory.
+ * @li The A20 line has to be activated, because all the code is beyong 1MB.
+ * @li Paging must be disabled.
+ * @li The SS, DS, and CS must span the whole 4GB of RAM.
+ * @li 32 bit protected mode must be entered.
+ * @li Interrupts must be disabled.
  */
 void x86_startup(void) NORETURN;
 
@@ -90,8 +90,8 @@ void x86_startup(void) NORETURN;
  * Interrupts may be enabled during the course of this function call.
  *
  * Probably most of the board specific initialization should be done in auto_init():
- * <li>You must not spawn thread_create() in this function.
- * <li>The hwtimer is not set up properly at this point of executation.
+ * @li You must not spawn thread_create() in this function.
+ * @li The hwtimer is not set up properly at this point of executation.
  */
 void x86_init_board(void);
 

cpu/x86/include/x86_rtc.h

@@ -115,9 +115,9 @@ typedef union x86_rtc_data {
  * You must not call this function on your own accord.
  *
  * The RTC subsystem will refuse to work if the CMOS says that
- * <li>there was a power loss,
- * <li>the stored time is invalid (i.e. February 30), or
- * <li>the CMOS had a checksum failure.
+ * @li there was a power loss,
+ * @li the stored time is invalid (i.e. February 30), or
+ * @li the CMOS had a checksum failure.
  */
 void x86_init_rtc(void);