Add a pattern for making shared ownership explicit. (#321)

Add a pattern for making shared ownership explicit.

In cases where projects are already owned by multiple teams but without clear
explicit Trusted Committers this pattern can help to bootstrap an initial set of
TCs.

Author: MaineC

patterns/1-initial/explicit-shared-ownership.md

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+# Title
+
+Explicit Shared Ownership
+
+# Patlet
+
+A software component that several teams depend on has grown to the point where owners are no longer capable of taking full ownership. There is confusion who to involve for changes. Sharing ownership explicitly and making expected behaviour visible removes ambiguity. Writing a contributions document creates a natural way to evolve ownership.
+
+# Problem
+
+An organisation is already using InnerSource best practices in several teams. The architecture of the software offered has grown organically.
+
+While talking about code ownership and accountability, teams notice that there is a component that is in a worrying state: Developed by an original team of authors it has grown it's userbase way beyond what the original team can handle. From time to time others step up to help out, however there is no formal process established. As a result, conflicts arise around who should do the work, and who should decide on project direction.
+
+Simply forking the component would lead to a lot of duplication and wasted effort. Therefore the involved teams are looking for a less intrusive solution to the issue.
+
+# Context
+
+- Teams are working independently but are providing one common platform as a service.
+
+- The software they are working on has been evolving for a long time. Engineers working on sub-modules have changed over time.
+
+- One component is in widespread use but ownership is unclear.
+
+# Forces
+
+- Ownership of one component is unclear.
+
+- There are too many teams dependent on the component to pull everyone into one single meeting to discuss ownership.
+
+- There may be people dependent on the module that are not yet known.
+There often is fear around maintenance efforts arising from unwanted attribution to the project.
+
+# Solution
+
+Use the issue/ pull-request mechanics that work so well for code modifications to modify the way the component is developed:
+
+A volunteer creates an issue in the component's repository highlighting the apparent unclarity or even lack of ownership. Subsequently a volunteer (can be the same person) creates a suggestion for how the project should be developed going forward including a proposed list of initial [Trusted Committers](../2-structured/trusted-committer.md). This suggestion is posted to the project's documentation (e.g. it's `README.md` file) as a pull request. This pull request is left open and shared with all people affected by the change. Feedback can be given and integrated asynchronously. Development of the final state is transparent for everyone.
+
+# Resulting Context
+
+There is an initial team of [Trusted Committers](../2-structured/trusted-committer.md) committed to the component.
+
+Expectations related to collaboration are transparent for everyone involved going forward e.g. by creating [base documentation in CONTRIBUTING.md](../2-structured/project-setup/base-documentation.md).
+
+The entire decision process backing the result is transparent and can be influenced by those affected, leading to higher buy-in for the final result. Also the argument leading to the final decisions are accessible for those new to the project.
+
+There is a proven way to adjust the setup in the future.
+
+# Status
+
+Initial (early draft)