fix filename in docstring, add magtag to readme

Author: FoamyGuy

README.rst

@@ -13,7 +13,7 @@ Introduction
     :target: https://github.com/adafruit/Adafruit_CircuitPython_PyBadger/actions/
     :alt: Build Status
 
-Badge-focused CircuitPython helper library for PyBadge, PyBadge LC, PyGamer and CLUE.
+Badge-focused CircuitPython helper library for PyBadge, PyBadge LC, PyGamer, CLUE, and Mag Tag.
 
 
 Dependencies

adafruit_pybadger/mag_tag.py

@@ -20,7 +20,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 """
-`adafruit_pybadger.clue`
+`adafruit_pybadger.mag_tag`
 ================================================================================
 
 Badge-focused CircuitPython helper library for Mag Tag.