tools: add operator example for split region#866

Merged

lilin90 merged 4 commits intopingcap:masterfrom

hicqu:document-split

Oct 9, 2018

Commits on Sep 4, 2018

Commits on Sep 30, 2018

Merge branch 'master' into document-split
hicqu
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Commits on Oct 8, 2018

address comments.
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