Add Version getter for index reader
Add Version getter for index reader

prometheus/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,prometheus/tsdb,GoogleCloudPlatform/prometheus,Gouthamve/prometheus,Gouthamve/prometheus,alileza/prometheus,prometheus/prometheus,prometheus/prometheus,keegancsmith/prometheus,alileza/prometheus,keegancsmith/prometheus,prometheus/prometheus,alileza/prometheus,kangwoo/prometheus,keegancsmith/prometheus,kangwoo/prometheus,Gouthamve/prometheus,kangwoo/prometheus,kangwoo/prometheus,keegancsmith/prometheus,Gouthamve/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus,keegancsmith/prometheus,Gouthamve/tsdb,alileza/prometheus,prometheus/prometheus