More clarification around Docker and conformance tests

ENVIRONMENT.md

@@ -8,10 +8,10 @@ for those scripts.
 
 Installing some of the dependencies can be tricky, particularly on
 restricted internal versions of Linux. For that reason, we provide a
-[Dockerfile](docker/Dockerfile) to get started with. The typical
-procedure would be:
+[Dockerfile](docker/Dockerfile) to get started with, which has
+`bash` as an entry point. The typical procedure would be:
 
-- `git clone https://github.com/googleapis/google-cloud-dotnet.git`
+- `git clone --recursive https://github.com/googleapis/google-cloud-dotnet.git`
 - `cd google-cloud-dotnet`
 - `docker build -t google-cloud-dotnet docker`
 - `docker run -v $PWD:/google-cloud-dotnet -it google-cloud-dotnet`

TESTING.md

@@ -40,6 +40,24 @@ be a bug in a test which wipes all the data in the project. It is
 *very strongly* recommended that you only run tests against projects
 which do not contain any production data or services.
 
+Initializing conformance test data
+==================================
+
+Cross-language conformance tests are defined in a [separate
+repository](https://github.com/googleapis/conformance-tests) which
+is referenced as a submodule within the google-cloud-dotnet
+repository.
+
+To ensure the submodule is suitably initialized and updated (so that
+the conformance test data is available locally) run this command:
+
+```sh
+git submodule update --init
+```
+
+(If your local `conformance-tests` directory contains files including a
+`README.md`, that probably means all is well.)
+
 Running tests via scripts
 =========================
 

docker/README.md

@@ -0,0 +1,11 @@
+Please see [ENVIRONMENT.md](../ENVIRONMENT.md) for details about
+this Dockerfile. The short version is:
+
+- It's intended to make it easy to perform builds, tests, releases
+  etc under Linux without modifying your local system.
+- It has an entry point of `bash` already
+- It expects `/google-cloud-dotnet` (in the container) to be a shared volume mount
+  using a clone of this repository.
+- Run the following commands from the repository root:
+  - `docker build -t google-cloud-dotnet docker`
+  - `docker run -v $PWD:/google-cloud-dotnet -it google-cloud-dotnet`