Remove reference to broken link

This was removed ages ago [1], with no clear replacement.

[1]: #1468

README.md

@@ -52,9 +52,6 @@ Pages are rendered using components. Components can be specific to government-fr
 
 Components specific to government-frontend are [within the application](https://github.com/alphagov/government-frontend/tree/master/app/views/components) and follow rules set out by the [govuk_publishing_components](https://github.com/alphagov/govuk_publishing_components) gem. They are documented in the [government-frontend component guide](https://government-frontend.herokuapp.com/component-guide).
 
-Configuration for the navigation links shown on the B variant of the ContentPagesNav A/B test is covered [separately](docs/navigation-links.md)
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-
 ### Further documentation
 
 - [Visual regression tests](docs/visual-regression-tests.md)