[DOCS] Use https for rpm packages, add dnf instructions
[DOCS] Use https for rpm packages, add dnf instructions

strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test,strapdata/elassandra-test