adding xteink x4 helper

Author: BlitzCityDIY

.gitmodules

@@ -1148,3 +1148,6 @@
 [submodule "libraries/drivers/sgp41"]
 	path = libraries/drivers/sgp41
 	url = https://github.com/adafruit/Adafruit_CircuitPython_SGP41.git
+[submodule "libraries/helper/xteink_x4"]
+	path = libraries/helper/xteink_x4
+	url = https://github.com/adafruit/Adafruit_CircuitPython_Xteink_X4.git

docs/drivers.rst

@@ -41,6 +41,7 @@ specific boards.
     Adafruit Qualia S3 (adafruit_qualia) <https://docs.circuitpython.org/projects/qualia/en/latest/>
     PyBadger (PyBadge and PyGamer) (adafruit_pybadger) <https://docs.circuitpython.org/projects/pybadger/en/latest/>
     MatrixPortal (Metro M4 Airlift + RGB Shield) (adafruit_matrixportal) <https://docs.circuitpython.org/projects/matrixportal/en/latest/>
+    Xteink X4 (adafruit_xteink_x4) <https://docs.circuitpython.org/projects/xteink_x4/en/latest/>
     YotoPlayer (adafruit_yotoplayer) <https://docs.circuitpython.org/projects/yotoplayer/en/latest/>
 
 Helper Libraries