Add breaking changes file into What's New

[janan07]

Describe your pull request here: This PR introduces content from zowe.org about breaking changes of Zowe components to be introduced in Zowe v3.

List the file(s) included in this PR: breaking-changes-v3.md, sidebars.js

After creating the PR, follow the instructions in the comments.

[github-actions]

😺 Thank you for creating this PR! To publish your content to Zowe Docs, follow these required steps.

• Add the label review: doc.
• Identify your content topic with a label. (Examples: area: apiml, area: cli, area: install and config, etc.)
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  • If adding content that needs to be removed from V3 documentation, add the V3 N/A tag.
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[github-actions]

📁 The PR description is missing the file name(s) for the updated content. List all the files included in this PR so this information displays in our Zowe Docs GitHub Slack channel.

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[github-actions]

📌 The subject area label is missing. Add an area: label so we know what your content is about.

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[github-actions]

🚀 Deployed on https://65ddd8f3f20ab90aefc0a7aa--zowe-docs-master.netlify.app

[balhar-jakub]

Removed a point that's not valid anymore
Clarified the API ML Update section