Scaling book reference cleanup

Author: bitschmidty

en/about.md

@@ -11,12 +11,11 @@ order to lower costs and improve customer experiences.
 
 An initial focus for the group is working with its member organizations to
 reduce transaction sizes and minimize the effect of subsequent transaction fee
-increases.  We provide [workshops][], [documentation][scaling book],
+increases.  We provide [workshops][],
 [weekly newsletters][], [original research][dashboard], [case studies
 and announcements][blog], a [podcast][], and help facilitate improved relations between
 businesses and the open source community.
 
-[scaling book]: https://github.com/bitcoinops/scaling-book
 [workshops]: /en/workshops
 [weekly newsletters]: /en/newsletters/
 [dashboard]: https://dashboard.bitcoinops.org/