Add 'Review of the latest Elyra Pipeline Editor improvements' blog post

[ptitzler]

Add new medium blog post to the Articles, blog posts, and other resources topic in the Getting started guide. The blog post should be accessible without the need to log in.

What changes were proposed in this pull request?

See above.

How was this pull request tested?

Reviewed the output of make docs

Developer's Certificate of Origin 1.1

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   (b) The contribution is based upon previous work that, to the best
       of my knowledge, is covered under an appropriate open source
       license and I have the right under that license to submit that
       work with modifications, whether created in whole or in part
       by me, under the same open source license (unless I am
       permitted to submit under a different license), as indicated
       in the file; or

   (c) The contribution was provided directly to me by some other
       person who certified (a), (b) or (c) and I have not modified
       it.

   (d) I understand and agree that this project and the contribution
       are public and that a record of the contribution (including all
       personal information I submit with it, including my sign-off) is
       maintained indefinitely and may be redistributed consistent with
       this project or the open source license(s) involved.

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