docs: adjust plugin dev guide example to write modified contents, fixes #3655#3656

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haoqunjiang merged 2 commits intovuejs:docsfrom

akrawchyk:3655-fix-plugin-dev-guide-example

Mar 20, 2019

Commits on Mar 18, 2019

adjust plugin dev guide example to write modified contents; fixes(#3655)
akrawchyk
committed

Commits on Mar 19, 2019

Update docs/dev-guide/plugin-dev.md

haoqunjiang
and
akrawchyk
authored