docs: discard the message for the people of Russia, but keep the stand with Ukraine flag

The message was written in 2022, and it is no longer possible that Russian people do
not know what is going on in Ukraine.  The letter I wrote in 2022 no longer carries any
useful value, but the banner still signifies support, and includes links to donations
and other informative sites for anyone who actually wants to make a difference.

Author: gdamore

README.md

@@ -16,8 +16,6 @@ It was inspired by _termbox_, but includes many additional improvements.
 [![Go Report Card](https://goreportcard.com/badge/github.com/gdamore/tcell/v2)](https://goreportcard.com/report/github.com/gdamore/tcell/v2)
 [![Latest Release](https://img.shields.io/github/v/release/gdamore/tcell.svg?logo=github&label=)](https://github.com/gdamore/tcell/releases)
 
-Please see [here](UKRAINE.md) for an important message for the people of Russia.
-
 NOTE: This is version 2 of _Tcell_. There are breaking changes relative to version 1.
 Version 1.x remains available using the import `github.com/gdamore/tcell`.