Moving notice for the stratum dependencies (#304)

Signed-off-by: Derek G Foster <[email protected]>

README.md

@@ -9,8 +9,16 @@ It is the successor to P4-OVS.
 P4 Control Plane modularizes P4-OVS and reduces coupling between its
 components, making the code easier to maintain and more suitable for
 upstreaming.
-It moves the P4-specific components of the architecture to a separate
-process called `infrap4d`.
+
+It moves the P4-specific components of the architecture from `ovs-vswitchd`
+to a separate process called `infrap4d`.
+
+## Upcoming changes
+
+The Stratum dependencies will be moving from the `setup` directory to
+a separate `stratum-deps` repository towards the end of October 2023.
+
+See the setup directory's [README file](setup/README.md) for more information.
 
 ## Source code
 

setup/README.md

@@ -0,0 +1,42 @@
+# Stratum Dependencies
+
+Stratum is the component of `infrap4d` that implements the P4Runtime and gNMI
+(OpenConfig) services.
+
+This directory allows you to build and install the third-party libraries
+that Stratum requires.
+
+<!-- markdownlint-disable-next-line -->
+## We're Moving!
+
+The Stratum dependencies are being relocated to their own repository,
+<https://github.com/ipdk-io/stratum-deps>.
+
+This allows the dependencies to be updated independently of the Networking
+Recipe (P4 Control Plane).
+
+### Development
+
+New development is currently taking place in the `stratum-deps` repository.
+
+See the
+[change history](https://github.com/ipdk-io/stratum-deps/blob/main/docs/change-history.md)
+for more information.
+
+### Transition
+
+We plan to phase out the `networking-recipe/setup` directory toward the end
+of October 2023.
+
+If you would like to start using `stratum-deps` before then,
+[version 1.2.0](https://github.com/ipdk-io/stratum-deps/tree/v1.2.0)
+is a good place to start.
+
+### Documentation
+
+The `stratum-deps` repository includes updated versions of relevant sections
+of the user manual, plus new documentation on the helper scripts.
+
+See the repository's
+[README file](https://github.com/ipdk-io/stratum-deps/blob/main/README.md)
+for links to the documentation.