doxygen: add groups for all modules

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/tm1637/tm1637.h

@@ -46,11 +46,17 @@
 
 namespace upm {
 
+/**
+ * @brief tm1637 7-segment screen library
+ * @defgroup tm1637 libupm-tm1637
+ */
+
 /**
  * @brief C++ API for Seven segments screen
  *
  * This file defines the TM1637 C++ interface for lib4digitdisplay
  *
+ * @ingroup tm1637
  * @snippet 4digitdisplay.cxx Interesting
  *
  *      A