[CMSP-967] Release Note for Pantheon MU Plugin 1.3.4

[jazzsequence]

Summary

Release Notes - Adds release note for Pantheon MU Plugin 1.3.4 which will be released after https://github.com/pantheon-systems/pantheon-mu-plugin/pull/35 is merged.

Remaining Work and Prerequisites

• [ ] Release Pantheon MU Plugin 1.3.4

Dependencies and Timing

• [x] https://github.com/pantheon-systems/pantheon-mu-plugin/pull/35 is merged and a new release is created

Release:

• [x] When ready
• [ ] After date: $DATE

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Post Launch

Do not remove - To be completed by the docs team upon merge:

• [ ] Redirect /old-path/ => /new-path/ (if applicable)
• [ ] Include/exclude pages ^ respectively within docs search service provider (if applicable)
• [ ] For Heroes - add a props post to the discussion board.
• [ ] Remove from the project board