docs: Add a Sponsors.md file

Add a documentation page with information on how to support Klipper.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

docs/Sponsors.md

@@ -0,0 +1,30 @@
+# Sponsors
+
+Klipper is Free Software. We depend on the generous support from
+sponsors. Please consider sponsoring Klipper or supporting our
+sponsors.
+
+## Klipper Developers
+
+### Kevin O'Connor
+
+Kevin is the original author and current maintainer of Klipper.  Kevin
+has a Patreon page at:
+[https://www.patreon.com/koconnor](https://www.patreon.com/koconnor)
+
+### Eric Callahan
+
+Eric is the author of bed_mesh, spi_flash, and several other Klipper
+modules.  Eric has a donations page at:
+[https://ko-fi.com/arksine](https://ko-fi.com/arksine)
+
+## Related Klipper Projects
+
+Klipper is frequently used with other Free Software. Consider using or
+supporting these projects.
+
+* [Moonraker](https://github.com/Arksine/moonraker)
+* [Mainsail](https://github.com/mainsail-crew/mainsail)
+* [Fluidd](https://github.com/fluidd-core/fluidd)
+* [OctoPrint](https://octoprint.org/)
+* [KlipperScreen](https://github.com/jordanruthe/KlipperScreen)