Update README: Add Comparison of Classic Editor vs. Gutenberg Exports for InDesign Imports

[frankiebordone]

Description of the Change

This PR updates the README to include a new section that details the differences between Classic Editor and Gutenberg (Block Editor) exports when imported into InDesign. The goal is to help users understand how each type of export behaves during import, particularly regarding additional block metadata in Gutenberg exports and the potential need for manual adjustments when importing into design tools like InDesign.

Closes #43

Changelog Entry

Added - Documentation update in the README to compare Classic Editor vs. Gutenberg (Block Editor) XML exports for InDesign imports.

Credits

Props @frankiebordone

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added Critical Flows, Test Cases, and/or End-to-End Tests to cover my change.
• All new and existing tests pass.

[dkotter]

@frankiebordone Realized after merging this in that we didn't make the same additions to the readme.txt file, which I think we'll want to do: https://github.com/10up/eight-day-week/blob/develop/readme.txt#L35

[frankiebordone]

@frankiebordone Realized after merging this in that we didn't make the same additions to the readme.txt file, which I think we'll want to do: https://github.com/10up/eight-day-week/blob/develop/readme.txt#L35

Great catch @dkotter! Updated here: #160