Add arm regression test badge into README
Add arm regression test badge into README

I have setup a periodic task in openlab env for gpdb.
It runs installcheck-world per UTC12:00 every day.

We can check the status with link

https://status.openlabtesting.org/builds/builds?project=greenplum-db%2Fgpdb&job_name=gpdb-installcheck-world-tests-on-arm64

And get the necessary log in each build.
Also that build definition could be changed anytime. You guys can tell me
the changes you want. Thanks

jmcatamney/gpdb,50wu/gpdb,adam8157/gpdb,50wu/gpdb,lisakowen/gpdb,50wu/gpdb,50wu/gpdb,adam8157/gpdb,greenplum-db/gpdb,lisakowen/gpdb,xinzweb/gpdb,jmcatamney/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,adam8157/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,adam8157/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,xinzweb/gpdb,50wu/gpdb,50wu/gpdb,greenplum-db/gpdb,lisakowen/gpdb,xinzweb/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb,lisakowen/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,adam8157/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb,greenplum-db/gpdb,lisakowen/gpdb,xinzweb/gpdb,xinzweb/gpdb,adam8157/gpdb,adam8157/gpdb,jmcatamney/gpdb,jmcatamney/gpdb