nicla-system: Add documentation to LDO functions.

Author: sebromero

libraries/Nicla_System/src/Nicla_System.cpp

@@ -84,7 +84,7 @@ bool nicla::enable1V8LDO()
 bool nicla::disableLDO()
 {
   uint8_t ldo_reg = _pmic.getLDOControlRegister();
-  ldo_reg &= 0x7F;
+  ldo_reg &= 0x7F; // Zeroes the EN_LS_LDO bit to turn it off
   _pmic.writeByte(BQ25120A_ADDRESS, BQ25120A_LDO_CTRL, ldo_reg);
   return _pmic.getLDOControlRegister() == ldo_reg;
 }

libraries/Nicla_System/src/Nicla_System.h

@@ -39,8 +39,29 @@ class nicla {
 
 public:
   static bool begin(bool mountedOnMkr = false);
+
+  /**
+   * @brief Enables the 3.3V LDO voltage regulator.
+   * 
+   * @return true if the LDO is enabled successfully. 
+   * This is done by verifying that the register was written correctly.
+   */
   static bool enable3V3LDO();
+
+  /**
+   * @brief Enables the 1.8V LDO voltage regulator.
+   * 
+   * @return true if the LDO is enabled successfully. 
+   * This is done by verifying that the register was written correctly.
+   */
   static bool enable1V8LDO();
+
+  /**
+   * @brief Disables the LDO voltage regulator.
+   * 
+   * @return true if the LDO is disabled successfully. 
+   * This is done by verifying that the register was written correctly.
+   */
   static bool disableLDO();
 
   /**