Improve pico_low_power brief (#3056)

src/rp2_common/pico_low_power/include/pico/low_power.h

diff --git a/src/rp2_common/pico_low_power/include/pico/low_power.h b/src/rp2_common/pico_low_power/include/pico/low_power.h
index 26f693f..0e89d25 100644
--- a/src/rp2_common/pico_low_power/include/pico/low_power.h
+++ b/src/rp2_common/pico_low_power/include/pico/low_power.h
@@ -19,7 +19,7 @@
 /** \file low_power.h
  *  \defgroup pico_low_power pico_low_power
  *
- * \brief Lower Power APIs
+ * \brief APIs for using lower power states.
  *
  * There are three modes of operation: sleep, dormant, and Pstate, with the lowest power consumption being Pstate.
  *