Writing updated toc.md for the en book

Author: spier

book/en/toc.md

@@ -31,6 +31,7 @@ Instead edit toc_template.md
 * [Extensions for Sustainable Growth](../../patterns/2-structured/extensions-for-sustainable-growth.md) - An InnerSource project is receiving too many contributions, making maintenance difficult. By offering an extension mechanism outside of the core project, the maintainers enable scaling of project capabilities with minimal cost and maintenance overhead.
 * [Gig Marketplace](../../patterns/2-structured/gig-marketplace.md) - Establish a marketplace by creating an intranet website that lists specific InnerSource project needs as "Gigs" with explicit time and skill requirements.  This will enable managers to better understand their employee’s time commitment and professional benefits thereby increasing the likelihood of garnering approval to make InnerSource contributions.
 * [Group Support](../../patterns/2-structured/group-support.md) - What happens if a team or individual no longer supports an InnerSource project? Keep the project alive by forming a group of interested individuals.
+* [InnerSource Hackathon](../../patterns/2-structured/innersource-hackathon.md) - Only InnerSource enthusiasts practice InnerSource during the early stages of adoption, while most engineering teams lack the time or motivation to try it. Hosting a company-wide hackathon focused on InnerSource contributions provides a safe space for engineers to experiment with InnerSource practices and produces tangible contributions to InnerSource projects.
 * [InnerSource License](../../patterns/2-structured/innersource-license.md) - Two legal entities that belong to the same organization want to share software source code with each other but they are concerned about the implications in terms of legal liabilities or cross-company accounting. An InnerSource License provides a reusable legal framework for the sharing of source code within the organization. This opens up new collaboration options, and makes the rights and obligations of the involved legal entities explicit.
 * [InnerSource Portal](../../patterns/2-structured/innersource-portal.md) - Potential contributors cannot easily discover InnerSource projects that they are interested in. By creating an intranet website that indexes all available InnerSource project information you enable contributors to learn about projects that might interest them and InnerSource project owners to attract an outside audience.
 * [Issue Tracker Use Cases](../../patterns/2-structured/issue-tracker.md) - The InnerSource host team fails to make not only plans and progress but also context for changes transparent. This is solved by increasing the use cases for the project issue tracker to also serve brainstorming, implementation discussion, and feature design.