Add CircuitPython_Waveform library

Author: relic-se

.gitmodules

@@ -463,3 +463,6 @@
 [submodule "libraries/helpers/iperf"]
 	path = libraries/helpers/iperf
 	url = https://github.com/bablokb/circuitpython-iperf.git
+[submodule "libraries/helpers/waveform"]
+	path = libraries/helpers/waveform
+	url = https://github.com/relic-se/CircuitPython_Waveform.git

circuitpython_community_library_list.md

@@ -145,6 +145,7 @@ c* [CircuitPython_RotarySelect](https://github.com/FoamyGuy/CircuitPython_Rotary
 * [CircuitPython TZDB](https://github.com/evindunn/circuitpython_tzdb) IANA timezones for adafruit_datetime ([PyPi](https://pypi.org/project/circuitpython-tzdb/)) \([Docs](https://circuitpython-tzdb.readthedocs.io/en/latest/))
 * [CircuitPython uplot](https://github.com/jposada202020/CircuitPython_uplot) Plot library for CircuitPython ([PyPi](https://pypi.org/project/circuitpython-uplot/)) \([Docs](https://circuitpython-uplot.readthedocs.io/en/latest/))
 * [CircuitPython_WaveBuilder](https://github.com/CedarGroveStudios/CircuitPython_WaveBuilder.git) A CircuitPython class to construct a composite synthio wave table from a collection of oscillators. \([Docs](https://github.com/CedarGroveStudios/CircuitPython_WaveBuilder/blob/main/media/pseudo_rtd_cedargrove_wavebuilder.pdf))
+* [CircuitPython_Waveform](https://github.com/relic-se/CircuitPython_Waveform.git) Helper library to generate simple and composite waveforms for use with synthio. \([Docs](https://circuitpython-waveform.readthedocs.io/))
 * [CircuitPython_WaveViz](https://github.com/CedarGroveStudios/CircuitPython_WaveViz.git) A CircuitPython class to create a positionable displayio.Group graphics widget from a synthio wave table. \([Docs](https://github.com/CedarGroveStudios/CircuitPython_WaveViz/blob/main/media/pseudo_rtd_cedargrove_waveviz.pdf))
 * [Gamblor21 CircuitPython AHRS](https://github.com/gamblor21/Gamblor21_CircuitPython_AHRS.git) This library contains right now one algorithm for AHRS - Attitude and Heading Reference System \([Docs](https://circuitpython-ahrs.readthedocs.io/))
 * [Jepler CircuitPython udecimal](https://github.com/jepler/Jepler_CircuitPython_udecimal.git) Reduced version of the decimal library for CircuitPython ([PyPi](https://pypi.org/project/jepler-circuitpython-udecimal)) \([Docs](https://jepler-udecimal.readthedocs.io/en/latest/))