Switch to subprojects for driver docs.

Author: tannewt

docs/drivers.rst

@@ -8,8 +8,8 @@ These are drivers available in separate GitHub repos.
     Register Library <http://adafruit-micropython-register.readthedocs.io/en/latest/>
     RGB Displays <http://micropython-rgb.readthedocs.io/>
     Analog-to-digital converters: ADS1015 and ADS1115 <http://micropython-ads1015.readthedocs.io/>
-    Real-time Clock modules <http://micropython-urtc.readthedocs.io/>
-    DS3231 Real-time Clock <http://adafruit-micropython-ds3231.readthedocs.io/en/latest/>
+    DS3231 Real-time Clock (Precision RTC) </projects/ds3231/en/latest/>
+    PCF8523 Real-time Clock (Adalogger RTC) </projects/pcf8523/en/latest/>
     TCS34725 Color Sensor <http://micropython-tcs34725.readthedocs.io/>
     TSL2561 Light Sensor <http://micropython-tsl2561.readthedocs.io/>
     PCA9685 Motor and Servo Controllers <http://micropython-pca9685.readthedocs.io/>