JS SDK blog post and tutorial improvements

[anuveyatsu]

Last improvements for JS SDK tutorial - https://datahub.io/docs/tutorials/js-sdk-tutorial and blog post about it.

Acceptance criteria

• [x] the tutorial is simplified
• [x] a blog post at /blog/...

Tasks

• [x] review the tutorial
• [x] improve language and simplify it, e.g., make it shorter with assumptions that users don't need an overview and other off-topic things - they want to deploy data
• [x] write a blog post draft
• [x] get it reviewed
• [x] publish

[anuveyatsu]

FIXED - https://datahub.io/blog/javascript-sdk-for-data-deployment