Remove Flesch reading ease from the assessments documentation

[agnieszkaszuba]

Context

• Flesch reading ease was moved to Insights so it shouldn't be included in the assessment documentation in the yoastseo package.

Summary

This PR can be summarized in the following changelog entry:

• Removes Flesch reading ease from the assessments documentation.
• [yoast-seo] Removes Flesch reading ease from the assessments documentation.

Relevant technical choices:

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

• Check whether the changes are formatted correctly here: SCORING_READABILITY.md

Relevant test scenarios

• Changes should be tested with the browser console open
• Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
• Changes should be tested on different browsers
• Changes should be tested on multisite

Test instructions for QA when the code is in the RC

• QA should use the same steps as above.

QA can test this PR by following these steps:

• No QA testing needed, only documentation is affected.

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

UI changes

• This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Other environments

• This PR also affects Shopify. I have added a changelog entry starting with [shopify-seo], added test instructions for Shopify and attached the Shopify label to this PR.

Documentation

• I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

Quality assurance

• I have tested this code to the best of my abilities.
• During testing, I had activated all plugins that Yoast SEO provides integrations for.
• I have added unit tests to verify the code works as intended.
• If any part of the code is behind a feature flag, my test instructions also cover cases where the feature flag is switched off.
• I have written this PR in accordance with my team's definition of done.
• I have checked that the base branch is correctly set.

Innovation

• No innovation project is applicable for this PR.
• This PR falls under an innovation project. I have attached the innovation label.
• I have added my hours to the WBSO document.

Fixes #

[coveralls]

Pull Request Test Coverage Report for Build 35c2c834afa8e943a4b00af8c37f43bafcd8ea86

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 53.551%

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Totals
Change from base Build 5aacf980d16efe949b0f7268c7588552e1bcec77:	0.0%
Covered Lines:	30658
Relevant Lines:	58068

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💛 - Coveralls

[Jordi-PV]

CR + AT 👍 Good job!