docs: introduce incubation repositories

This PR describes the role and usage of incubation repositories.

docs/features/integration/index.rst

@@ -58,6 +58,30 @@ Optional repositories:
 
 -  repositories containing implementation of particular features
 
+Incubation repositories
+=======================
+
+For early evaluation of existing implementations and prototypes we introduce
+so called `incubation repositories`.
+They should serve as a prototyping area where developers can share and build
+code with only limited restrictions such quality KPIs, review process, etc.
+
+Incubation repositories are indicated by the suffix `inc_` in the repo name.
+
+Any incubation repository shall evolve over time towards a fully functional
+bazel module, which can be integrated via an additonal dependencies in the main
+build.
+
+If a repo has reached this state and the concept is approved in general the
+content can be merged into the `score` repository. In this stage the content
+of shall still be disabled via a bazel `feature flag`.
+This `feature flag` shall follow the nameing convention
+`//experimental_[feature]`. The `experimental`-suffix indicates to the user that
+this functionality is not yet ready for series production.
+Additionally the relevant code might not meet all required quality KPIs.
+
+
+
 References
 ==========