message: docs: shrink GIF caption text
diff: <div align="center">
  <img src="assets/demo.gif" alt="Quick demo recording showing off bottom's searching, expanding, and process killing."/>
  <p>
  + <sub>
  Demo GIF using the <a href="https://github.com/morhetz/gruvbox">Gruvbox</a> theme (<code>--color gruvbox</code>), along with <a href="https://www.ibm.com/plex/">IBM Plex Mono</a> and <a href="https://sw.kovidgoyal.net/kitty/">Kitty</a>
  + </sub>
  </p>
  </div>
  