add optional requirement and fix docs build

Author: FoamyGuy

docs/conf.py

@@ -39,8 +39,9 @@
     "busdisplay",
     "busio",
     "digitalio",
-    "displayio" "espcamera",
+    "espcamera",
     "fourwire",
+    "jpegio",
     "micropython",
     "neopixel",
     "sdcardio",

docs/mock/displayio.py

@@ -9,3 +9,24 @@ def __init__(self, i):
 
     def __setitem__(self, idx, value):
         self._data[idx] = value
+
+
+class ColorConverter:
+    def __init__(self, colorspace):
+        self._colorspace = colorspace
+
+    def convert(self, color_value) -> int:
+        pass
+
+
+class Bitmap:
+    def __init__(self, width, height, color_count):
+        pass
+
+
+class Colorspace:
+    pass
+
+
+class Display:
+    pass

optional_requirements.txt

@@ -1,3 +1,5 @@
 # SPDX-FileCopyrightText: 2022 Alec Delaney, for Adafruit Industries
 #
 # SPDX-License-Identifier: Unlicense
+
+adafruit_bitmapsaver