Transformer tutorial

[Styleoshin]

This is a little tutorial about how to use tensor2tensor for translation task. Because in first time its hard to understand how this library works.
I had to use this library for a project, I was wondering why not create a little tutorial at the same time, for help others.

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[review-notebook-app]

Check out this pull request on ReviewNB: https://app.reviewnb.com/tensorflow/tensor2tensor/pull/1675

You'll be able to see notebook diffs and discuss changes. Powered by ReviewNB.

[lukaszkaiser]

Thanks! Could you click the CLA part? (We need this to accept the PR - let us know if there're any problems with that.)

[Styleoshin]

@googlebot I signed it!

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We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for all the commit author(s) or Co-authors. If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.
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[Styleoshin]

@googlebot I fixed it.

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CLAs look good, thanks!

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[afrozenator]

Hi @Styleoshin -- First of all many thanks for volunteering to add this, we'd like to accept this.

But we require an Apache license at the start of all the files, will you be able to add that (see the other notebooks in this directory for an example)?

I can merge it in once you do that, all else looks in place.

Thanks

[Styleoshin]

Hi @afrozenator! So much.
I added the license.

[afrozenator]

Thanks @Styleoshin ! Will merge in shortly.