Add documentation for namespace

Fixes: #416

docs/reference/commandline/tye-deploy.md

@@ -7,7 +7,7 @@
 ## Synopsis 
 
 ```text
-tye deploy [-?|-h|--help] [-i|--interactive] [-v|--verbosity <Debug|Info|Quiet>] [-f|--force] [<PATH>]
+tye deploy [-?|-h|--help] [-i|--interactive] [-n|--namespace <n>] [-v|--verbosity <Debug|Info|Quiet>] [-f|--force] [<PATH>]
 ```
 
 ## Description
@@ -19,7 +19,13 @@ The `tye deploy` command will deploy an application to Kubernetes. `tye deploy`
 - Generate a Kubernetes Deployment and Service for each project.
 - Apply the generated Deployment and Service to your current Kubernetes context.
 
-`tye deploy` operates in the current Kubernetes namespace. Use `kubectl config view --minify --output 'jsonpath={..namespace}'` to view the current namespace.
+`tye deploy` chooses the Kubernetes namespace to operate in according to the following priority:
+
+- The value of `--namespace` passed at the command line
+- The value of `namespace` configured in `tye.yaml` (if present)
+- The Kubernetes namespace for the current context
+
+> :bulb: Use `kubectl config view --minify --output 'jsonpath={..namespace}'` to view the current namespace.
 
 ## Arguments
 
@@ -39,6 +45,10 @@ If a directory path is specified, `tye deploy` will default to using these files
 
     Does an interactive deployment that will accept input for values that are required by default.
 
+- `-n|--namespace`
+  
+    Specifies the Kubernetes namespace for deployment. Overrides a namespace value set in `tye.yaml`.
+
 - `-v|--verbosity <Debug|Info|Quiet>`
 
     The verbosity of logs emitted by `tye deploy`. Defaults to Info.

docs/reference/commandline/tye-undeploy.md

@@ -7,7 +7,7 @@
 ## Synopsis 
 
 ```text
-tye undeploy [-?|-h|--help] [-i|--interactive] [-v|--verbosity <Debug|Info|Quiet>] [--what-if] [<PATH>]
+tye undeploy [-?|-h|--help] [-i|--interactive] [-n|--namespace <n>] [-v|--verbosity <Debug|Info|Quiet>] [--what-if] [<PATH>]
 ```
 
 ## Description
@@ -19,7 +19,13 @@ The `tye undeploy` command will delete a deployed application from Kubernetes. `
 - Offer a choice to delete each resource (interactive)
 - Delete each resource (if applicable)
 
-`tye undeploy` operates in the current Kubernetes namespace. Use `kubectl config view --minify --output 'jsonpath={..namespace}'` to view the current namespace.
+`tye undeploy` chooses the Kubernetes namespace to operate in according to the following priority:
+
+- The value of `--namespace` passed at the command line
+- The value of `namespace` configured in `tye.yaml` (if present)
+- The Kubernetes namespace for the current context
+
+> :bulb: Use `kubectl config view --minify --output 'jsonpath={..namespace}'` to view the current namespace.
 
 Undeploy decides which resources to delete based on the `app.kubernetes.io/part-of=...` label. This label will be set to the application name for all resources created by Tye. `tye undeploy` does not rely on the list of services in `tye.yaml` or a solution file. 
 
@@ -41,6 +47,10 @@ If a directory path is specified, `tye undeploy` will default to using these fil
 
     Does an interactive undeploy that will prompt for deletion of each resource.
 
+- `-n|--namespace`
+  
+    Specifies the Kubernetes namespace for deployment. Overrides a namespace value set in `tye.yaml`.
+
 - `-v|--verbosity <Debug|Info|Quiet>`
 
     The verbosity of logs emitted by `tye undeploy`. Defaults to Info.

docs/reference/schema.md

@@ -46,6 +46,7 @@ services:
 ```yaml
 name: myapplication
 registry: exampleuser
+namespace: examplenamespace
 services:
 ```
 
@@ -68,6 +69,14 @@ The registry could be a DockerHub username (`exampleuser`) or the hostname of a
 
 If this is not specified in configuration, interactive deployments will prompt for it.
 
+#### `namespace` (string)
+
+Allows configuring the Kubernetes namespace used by commands that operate on Kubernetes. If unconfigured, Tye will use the namespace of the current Kubernetes context.
+
+The namespace specified in `tye.yaml` can be overridden at the command line.
+
+> :bulb: Use `kubectl config view --minify --output 'jsonpath={..namespace}'` to view the current namespace.
+
 #### `services` (`Service[]`) *required*
 
 Specifies the list of services. Applications must have at least one service.

src/schema/tye-schema.json

@@ -13,6 +13,10 @@
             "description": "Dockerhub username or hostname of remote registry. Used for tagging images.",
             "type": "string"
         },
+        "namespace": {
+            "description": "The Kubernetes namespace to use.",
+            "type": "string"
+        },
         "services": {
             "description": "The application's services.",
             "type": "array",