VS Code schema validation (#884)

## Description

<!-- Please include a summary of the change. Any relevant motivation or
context is also helpful, as well as any dependencies that are required
for this change -->

Add documentation to be able to use `zarf.schema.json` as YAML
validation for `zarf.yaml` in VS Code.

## Related Issue

<!--- This project prefers to accept pull requests related to open
issues -->
<!--- If suggesting a new feature or change, please discuss it in an
issue first -->
<!--- If fixing a bug, there should be an issue describing it with steps
to reproduce -->

Fixes #872 

## Type of change

<!-- Please delete options that are not relevant -->

- [x] Documentation addition / change

## Checklist before merging

<!-- Please delete options that are not relevant -->

- [x] Documentation has been updated as necessary (add the `needs-docs`
label)

Co-authored-by: Megamind <[email protected]>

docs/4-user-guide/4-vscode.md

@@ -0,0 +1,32 @@
+# Getting started - VS Code
+
+Zarf uses its own [schema](https://github.com/defenseunicorns/zarf/blob/master/zarf.schema.json) to define its configuration files. This schema is used to describe package configuration options and can be used to validate the configuration files before they are used to build a Zarf package.
+
+## Adding schema validation
+
+1. Open VS Code's `settings.json` file with `CTRL/CMD + SHIFT + P` and search for `Preferences: Open User Settings (JSON)`.
+2. Add the below to your config, or modify the existing `yaml.schemas` object to include the Zarf schema.
+
+:::note
+
+The [YAML extension](https://marketplace.visualstudio.com/items?itemName=redhat.vscode-yaml) by RedHat is a prerequisite for this feature.
+
+:::
+
+```json
+  "yaml.schemas": {
+    "https://github.com/defenseunicorns/zarf/raw/master/zarf.schema.json": "zarf.yaml"
+  }
+```
+
+## Specifying Zarf's schema version
+
+In some cases, it may be beneficial to lock a `zarf.yaml`'s validation to a specific version of the Zarf schema.
+
+This can be accomplished by adding the below to the **first** line of any given `zarf.yaml`.
+
+```yaml
+# yaml-language-server: $schema=https://github.com/defenseunicorns/zarf/raw/<VERSION>/zarf.schema.json
+```
+
+Where `<VERSION>` is one of [Zarf's releases](https://github.com/defenseunicorns/zarf/releases).