Fix a bunch of doxygen typos (#391)

src/rp2_common/hardware_dma/include/hardware/dma.h

@@ -353,7 +353,7 @@ static inline void dma_channel_set_read_addr(uint channel, const volatile void *
     }
 }
 
-/*! \brief  Set the DMA initial read address
+/*! \brief  Set the DMA initial write address
  *  \ingroup hardware_dma
  *
  * \param channel DMA channel

src/rp2_common/hardware_exception/include/hardware/exception.h

@@ -59,7 +59,7 @@ enum exception_number {
 /*! \brief Exception handler function type
  *  \ingroup hardware_exception
  *
- * All exceptions handlers should be of this type, and follow normal ARM EABI register saving conventions
+ * All exception handlers should be of this type, and follow normal ARM EABI register saving conventions
  */
 typedef void (*exception_handler_t)(void);
 

src/rp2_common/pico_standard_link/crt0.S

@@ -75,7 +75,7 @@ __vectors:
 .word isr_irq31
 
 // all default exception handlers do nothing, and we can check for them being set to our
-// default values by them pointing to between __defaults_isrs_start and __default_isrs_end
+// default values by seeing if they point to somewhere between __defaults_isrs_start and __default_isrs_end
 .global __default_isrs_start
 __default_isrs_start: