examples: added missing snippets and paired them with right examples

Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

src/pulsensor/pulsensor.h

@@ -39,6 +39,24 @@
 #define TRUE               HIGH
 #define FALSE              LOW
 
+
+/**
+ * @brief pulsensor pulse sensor library
+ * @defgroup pulsensor libupm-pulsensor
+ */
+
+/**
+ * @brief C++ API for 3-wire pulse sensor
+ *
+ * This is a library for the 3-wire pulse sensor sold by several manufacturers.
+ * Usually, you can identify the sensor based on the round breakout and the
+ * distinctive heart symbol. 
+ *
+ * @ingroup pulsensor analog
+ * @snippet pulsensor.cxx Interesting
+ */
+
+
 /*!
  * @struct clbk_data
  * @brief callback data