Add gruid-tcell to the list of examples in the README

gruid-tcell is a tcell-based driver for the grid-based UI and game
framework gruid.

README.adoc

@@ -53,6 +53,7 @@ Version 1.x remains available using the import `github.com/gdamore/tcell`.
 * https://github.com/a-h/min[min] - A Gemini browser
 * https://github.com/noborus/ov[ov] - Terminal pager
 * https://github.com/gcla/tmux-wormhole[tmux-wormhole] - A tmux plugin to transfer files with magic wormhole
+* https://github.com/anaseto/gruid-tcell[gruid-tcell] - A tcell driver for the grid based UI and game framework gruid.
 
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