Add intro text for Adopters section

adopters/README.md

@@ -1,5 +1,28 @@
 # Adopters
 
+Each pattern in this book has been contributed by an organization. That confirms that a single organization is using a given approach.
+
+However the idea of a pattern is that they provide repeatable, proven solution that other organizations can apply in their own context.
+Therefore these patterns become more powerful, when multiple organizations confirm that they have implemented a pattern.
+
+This provides a great low-friction way for all readers of this book to contribute!
+
+## Share your pattern adoption
+
+If you see a pattern in this book that you are using at your organization, please do the following:
+
+- on a given pattern page, click the 'Edit on GitHub' button
+- add your own organization to the 'Known Instances' section
+- then submit your changes as a Pull Request
+
+## Showcase your InnerSource approach
+
+Once the Pull Request with your changes has been merged, you will not only be listed on the pattern itself, but you will also get a dedicated page for your organization, showcasing all the patterns that you are using.
+
+See the pages below for all organization that have confirmed their adoption and implementation of some of our patterns.
+
+## Backup
+
 Implementation approachs:
 
 a)