(DOCS) Add resource capabilities reference doc

Prior to this change, the resource capabilities documentation was
only defined in the output for the `dsc resource list` command
reference. This change extracts the useful information into a
separate document, reflecting also the shared definition schema
added in the last release. This supports referencing the schema
from other schemas.

A future change will address updating those reference documents
as needed.

Author: michaeltlombardi

docs/reference/schemas/definitions/resourceCapabilities.md

@@ -0,0 +1,55 @@
+---
+description: JSON schema reference for resource capabilities
+ms.date:     07/03/2025
+ms.topic:    reference
+title:       DSC Resource capabilities schema reference
+---
+
+# DSC Resource capabilities schema reference
+
+## Synopsis
+
+Defines the operations you can invoke for a resource and how the resource behaves when invoked.
+
+## Metadata
+
+```yaml
+SchemaDialect:     https://json-schema.org/draft/2020-12/schema
+SchemaID:          https://raw.githubusercontent.com/PowerShell/DSC/main/schemas/v3.1.0/definitions/resourceKind.json
+Type:              array
+Required:          true
+ItemsMustBeUnique: true
+ItemsType:         string
+ItemsValidValues: [
+                    get,
+                    set,
+                    setHandlesExist,
+                    whatIf,
+                    test,
+                    delete,
+                    export,
+                    resolve
+                  ]
+```
+
+## Description
+
+DSC resources always have at least one capability. Resource capabilities define the operations you
+can invoke for a resource and how the resource behaves when invoked.
+
+DSC resources may have the following capabilities:
+
+- `get` - The resource can retrieve the current state of an instance.
+- `set` - The resource can enforce the desired state for an instance.
+- `setHandlesExist` - The resource handles deleting an instance during a **Set** operation.
+- `whatIf` - The resource can report how it would change state for an instance during a **Set** operation.
+- `test` - The resource implements the **Test** operation and doesn't rely on synthetic testing.
+- `delete` - The resource can remove an instance.
+- `export` - The resource can enumerate every instance.
+- `resolve` - The resource can resolve nested instances from an external source.
+
+For more information about resource capabilities, see [DSC resource capabilities][01]. For more
+information about the operations you can invoke for a resource, see [DSC resource operations][02].
+
+[01]: ../../../concepts/resources/capabilities.md
+[02]: ../../../concepts/resources/operations.md