Update TESTING.asciidoc with platform specific instructions (#38802)
Update TESTING.asciidoc with platform specific instructions (#38802)

This adds the instructions for building a platform-specific distribution.
vroyer/elassandra,strapdata/elassandra,strapdata/elassandra,vroyer/elassandra,strapdata/elassandra,strapdata/elassandra,strapdata/elassandra,vroyer/elassandra