Add simplemath

Author: dhalbert

.gitmodules

@@ -769,3 +769,6 @@
 [submodule "libraries/helpers/oauth_2"]
 	path = libraries/helpers/oauth_2
 	url = https://github.com/adafruit/Adafruit_CircuitPython_OAuth2.git
+[submodule "libraries/helpers/simplemath"]
+	path = libraries/helpers/simplemath
+	url = https://github.com/adafruit/Adafruit_CircuitPython_SimpleMath.git

docs/drivers.rst

@@ -196,6 +196,7 @@ Miscellaneous Helpers
     OneWire <https://circuitpython.readthedocs.io/projects/onewire/en/latest/>
     SD Card <https://circuitpython.readthedocs.io/projects/sd/en/latest/>
     SimpleIO <https://circuitpython.readthedocs.io/projects/simpleio/en/latest/>
+    SimpleMath <https://circuitpython.readthedocs.io/projects/simplemath/en/latest/>
     USB Human Interface Device (Keyboard and Mouse) <https://circuitpython.readthedocs.io/projects/hid/en/latest/>
     Test Repo <https://circuitpython.readthedocs.io/projects/testrepo/en/latest/>