HPCC-9504 Add README.1st file into testing/regress directory to describe how
to run Regression Suite

A short decription added.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
HPCC-9504 Add README.1st file into testing/regress directory to describe how
to run Regression Suite

Convert Readme.1st to README.rst.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>