op-guide: clarify offline behavior (#798)
op-guide: clarify offline behavior (#798)

* clarify offline behavior

* copy editing for op-guide/horizontal-scale.md

Co-Authored-By: gregwebs <79e2475f81a6317276bf7cbb3958b20d289b78df@gregweber.info>

pingcap/docs,pingcap/docs,pingcap/docs