DOC: Add steps to release from maintenance branch [skip ci]
DOC: Add steps to release from maintenance branch [skip ci]

bashtage/statsmodels,josef-pkt/statsmodels,statsmodels/statsmodels,josef-pkt/statsmodels,jseabold/statsmodels,statsmodels/statsmodels,jseabold/statsmodels,bashtage/statsmodels,statsmodels/statsmodels,jseabold/statsmodels,bashtage/statsmodels,josef-pkt/statsmodels,josef-pkt/statsmodels,jseabold/statsmodels,josef-pkt/statsmodels,bashtage/statsmodels,bashtage/statsmodels,statsmodels/statsmodels,bashtage/statsmodels,statsmodels/statsmodels,josef-pkt/statsmodels,statsmodels/statsmodels,jseabold/statsmodels