add adafruit_ticks into drivers.rst

 Has been added in #331 , but in drivers.rst is missing.

Author: Wind-stormger

docs/drivers.rst

@@ -213,6 +213,7 @@ Miscellaneous Helpers
     SimpleMath <https://circuitpython.readthedocs.io/projects/simplemath/en/latest/>
     Test Repo <https://circuitpython.readthedocs.io/projects/testrepo/en/latest/>
     USB HID - Human Interface Device (Keyboard and Mouse) <https://circuitpython.readthedocs.io/projects/hid/en/latest/>
+    Ticks <https://circuitpython.readthedocs.io/projects/ticks/en/latest/>
 
 Blinky
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