Add doc for deploy-webapp (#672)

docs/webapp.md

@@ -34,7 +34,7 @@ To test locally run:
 
 ## Running
 
-With `run-webapp` a new container will be launched with runtime configuration provided by `--env-file` (if specified) and published on an available port.  Multiple instances can be launched with different configuration.
+With `run-webapp` a new container will be launched on the local machine, with runtime configuration provided by `--env-file` (if specified) and published on an available port.  Multiple instances can be launched with different configuration.
 
 **Example**:
 ```
@@ -52,3 +52,13 @@ Image: cerc/test-progressive-web-app:local
 ID: 9ab96494f563aafb6c057d88df58f9eca81b90f8721a4e068493a289a976051c
 URL: http://localhost:32769
 ```
+
+## Deploying
+
+Use the subcommand `deploy-webapp create` to make a deployment directory that can be subsequently deployed to a Kubernetes cluster.
+Example commands are shown below, assuming that the webapp container image `cerc/test-progressive-web-app:local` has already been built:
+```
+$ laconic-so deploy-webapp create --kube-config ~/kubectl/k8s-kubeconfig.yaml --image-registry registry.digitalocean.com/laconic-registry --deployment-dir webapp-k8s-deployment --image cerc/test-progressive-web-app:local --url https://test-pwa-app.hosting.laconic.com/ --env-file test-webapp.env
+$ laconic-so deployment --dir webapp-k8s-deployment push-images
+$ laconic-so deployment --dir webapp-k8s-deployment start
+```

stack_orchestrator/deploy/deployment_context.py

@@ -16,6 +16,7 @@
 
 from pathlib import Path
 
+from stack_orchestrator import constants
 from stack_orchestrator.deploy.stack import Stack
 from stack_orchestrator.deploy.spec import Spec
 
@@ -26,13 +27,13 @@ class DeploymentContext:
     stack: Stack
 
     def get_stack_file(self):
-        return self.deployment_dir.joinpath("stack.yml")
+        return self.deployment_dir.joinpath(constants.stack_file_name)
 
     def get_spec_file(self):
-        return self.deployment_dir.joinpath("spec.yml")
+        return self.deployment_dir.joinpath(constants.spec_file_name)
 
     def get_env_file(self):
-        return self.deployment_dir.joinpath("config.env")
+        return self.deployment_dir.joinpath(constants.config_file_name)
 
     # TODO: implement me
     def get_cluster_name(self):