Rm non free resources

Author: Robert Felker

source.md

@@ -54,7 +54,6 @@ If you appreciate the content 📖, support projects visibility, give 👍| ⭐|
 - [Open Source Apps](#open-source-apps)
 - [Utilities](#utilities)
 - [Community](#community)
-- [Books](#books)
 - [Bonus](#bonus)
 
 ## Articles
@@ -515,11 +514,6 @@ If you appreciate the content 📖, support projects visibility, give 👍| ⭐|
 - [Golang Desktop Embedder](https://github.com/go-flutter-desktop/go-flutter) <!--stargazers:go-flutter-desktop/go-flutter--> - Golang embedder for desktop by [Pierre Champion](https://github.com/Drakirus)
 - [Rust Desktop Embedder](https://github.com/gliheng/flutter-rs) <!--stargazers:gliheng/flutter-rs--> - Rust embedder for desktop by [juju](https://github.com/gliheng).
 
-
-## Books
-
-- [Flutter in Action](https://www.manning.com/books/flutter-in-action?a_aid=flutterinaction&a_bid=d08c3247) - Complete Flutter and Dart resource, currently in 'Early Access'.
-
 ## Bonus
 
 - [It's All Widgets!](https://itsallwidgets.com) - Open list of published apps by [Hillel Coren](https://twitter.com/hillelcoren), [Thomas Burkhart](https://twitter.com/ThomasBurkhartB), [Simon Lightfoot](https://twitter.com/devangelslondon) and [Scott Stoll](https://twitter.com/scottstoll2017)