arrow

GH-44474: [Website] Improve project description (#44492)

Part 2 of 2 of #44474.

This updates the Apache Arrow project description that appears in the GitHub repo **About** information.
* GitHub Issue: #44474

Authored-by: Ian Cook <ianmcook@gmail.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>