Add hideakitai/ESP32SPISlave (#291)

Author: hideakitai

repositories.txt

@@ -1473,6 +1473,7 @@ https://github.com/hideakitai/Easing
 https://github.com/hideakitai/EmbeddedUtils
 https://github.com/hideakitai/ES920
 https://github.com/hideakitai/ESP32DMASPI
+https://github.com/hideakitai/ESP32SPISlave
 https://github.com/hideakitai/Filters
 https://github.com/hideakitai/HyperDeck
 https://github.com/hideakitai/I2CExtension