Add pattern 'Transitioning Contractor Code to InnerSource Model' to README (#466)

Author: spier

README.md

@@ -78,6 +78,7 @@ The below lists all known patterns. They are grouped into three [maturity levels
 * [Balancing Openness and Security](/patterns/1-initial/balancing-openness-and-security.md) - *While InnerSource flourishes in environments with a high degree of shared code, Security/Legal prefers the limitation of source code access to only those that need it. By making Security/Legal part of the team, introducing explicit sharing levels and security policies for shared repositories, as well as defining what qualifies as sensitive information, code sharing can be facilitated while minimizing the associated risks.*
 * [Crossing the InnerSource Chasm](/patterns/1-initial/crossing-chasm.md) - *Early InnerSource experiments have been successful. Methods that were successful convincing early teams stop working though when scaling the initiative. This chasm can be crossed by using different methods to reach people at different stages of the innovation curve.*
 * [Extensions to Manage Contributions at Scale](/patterns/1-initial/extensions-to-manage-contributions-at-scale.md) - *An InnerSource project is receiving too many contributions, making maintenance difficult and resulting in a large code review backlog or premature rejection of new feature contributions. By offering an extension mechanism outside of the core project, the maintainers enable scaling of project capabilities with minimal cost and maintenance overhead.*
+* [Transitioning Contractor Code to InnerSource Model](/patterns/1-initial/transitioning-contractor-code-to-innersource-model.md) - *Contract developers are often not motivated to engage in InnerSource activities, which may be beyond the scope of their contract. This pattern describes how you can focus on transitioning the contractor project after the fact to an InnerSource project by setting expectations for specific InnerSource-related deliverables as part of the overall project delivery.*
 
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 NOTE: The 'Initial' Patterns below don't even have a Patlet yet, which is essential for readers to quickly browse our patterns.