SSD1683 4-gray: trim PR-explainer references from example and driver comments

Address review feedback: rewrite the example docstring to match the #4197
grayscale example style and drop adafruit_epd PR #111 references from the
example and the DISP_CTRL1 comment.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mikeysklar

adafruit_ssd1680.py

@@ -113,7 +113,7 @@
     b"\x0c\x00\x04\x8b\x9c\xa4\x0f"  # BOOST_SOFTSTART
     b"\x11\x00\x01\x03"  # RAM data entry mode
     b"\x3c\x00\x01\x03"  # border
-    b"\x21\x00\x02\x00\x00"  # DISP_CTRL1 (no source-line shift; matches adafruit_epd PR #111)
+    b"\x21\x00\x02\x00\x00"  # DISP_CTRL1 (no source-line shift)
     b"\x3f\x00\x01\x07"  # END_OPTION
     b"\x03\x00\x01\x17"  # gate voltage
     b"\x04\x00\x03\x41\xa8\x32"  # source voltage

examples/ssd1683_4.2_grayscale_6381.py

@@ -2,11 +2,10 @@
 #
 # SPDX-License-Identifier: Unlicense
 
-"""4-gray grayscale info card for the Adafruit 4.2" 400x300 E-Ink Display (#6381).
+"""4-gray "ThinkInk" info card for the Adafruit 4.2" 400x300 E-Ink Display (#6381).
 
-displayio / SSD1683 driver. Layout mirrors the adafruit_epd PR #111 example:
-big built-in font (scale 3-4) and a tall 4-box gray ramp that fills the panel.
-FPC-190 ribbon. Tested on Adafruit Feather RP2040 ThinkInk.
+A grayscale take on the factory demo: product text plus a 4-level gray ramp
+(white / light / dark / black) that shows all four shades at once.
 """
 
 import time
@@ -60,7 +59,7 @@
 bg.fill(WHITE)
 g.append(displayio.TileGrid(bg, pixel_shader=pal))
 
-# Big text, sized to fill the 400px width (matches PR #111: scale 3-4)
+# Big text, sized to fill the 400px width
 texts = [
     ("Adafruit ThinkInk", 6, 10, 3, 0x000000),
     ('4.2" 400x300', 6, 50, 4, 0x000000),