fdo#80103 - A superlative adjective without an article in README_en-US

Change-Id: I2bfff87f6e67b72ba8d0aa46f9126c21dc0a0032
Reviewed-on: https://gerrit.libreoffice.org/9842
Reviewed-by: Adolfo Jayme Barrientos <fito@libreoffice.org>
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>