embed saku.md in README.md

[kt3k]

# Usage
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# Tasks

The followings are tasks for development. You can invoke them with `saku` command, such as `saku build`

## build
> Builds the bundles

    npx webpack

## serve

> Serves the development resources

    npx webpack-dev-server

# License
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[kt3k]

• The first heading which has the word tasks or task starts the definition of saku's tasks.
• If the heading above has level-n then the next level-(n+1) headings are definitions of tasks.
• If the task(s) heading has level-n then the next level-n heading ends the task definition.