examples: Replace some prebuilt graphics by images and scripts

examples/_original_assets/cinque_terre.txt

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+Link: https://unsplash.com/photos/Yy-srRFVgPA
+Author: Daniel J. Schwarz's
+License: Unsplash
+
+Cinque Terre, SP, Italy
+Published on March 26, 2023
+Canon, EOS 6D Mark II
+
+Already feels like summer here in Cinque Terre! 🌞

examples/demo/zoomx2/assets/convert.sh

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+#!/bin/sh
+grit img16_c.jpg -gb -gB16 -ftb

examples/demo/zoomx3/assets/convert.sh

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+#!/bin/sh
+grit img16_c.jpg -gb -gB16 -ftb

examples/graphics/bg8bits/assets/convert.sh

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+#!/bin/sh
+grit img8b_3.jpg -gb -gB8 -ftb

licenses/unsplash.txt

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+Unsplash License
+================
+
+Unsplash photos are made to be used freely. Our license reflects that.
+
+- All photos can be downloaded and used for free
+- Commercial and non-commercial purposes
+- No permission needed (though attribution is appreciated!)
+
+What is not permitted
+
+- Photos cannot be sold without significant modification.
+- Compiling photos from Unsplash to replicate a similar or competing service.
+
+Longform
+--------
+
+Unsplash grants you an irrevocable, nonexclusive, worldwide copyright license to
+download, copy, modify, distribute, perform, and use photos from Unsplash for
+free, including for commercial purposes, without permission from or attributing
+the photographer or Unsplash. This license does not include the right to compile
+photos from Unsplash to replicate a similar or competing service.
+
+Tip: How to give attribution
+----------------------------
+
+Even though attribution isn’t required, Unsplash photographers appreciate it as
+it provides exposure to their work and encourages them to continue sharing.
+
+    Photo by Jeremy Bishop on Unsplash