[PKG-7403] - API docs for registries create

pages/apis/rest_api/packages/registries.md

@@ -2,6 +2,56 @@
 
 The registries API lets you create and manage registries in your organization.
 
+## Create a registry
+
+```bash
+curl -H "Authorization: Bearer $TOKEN" \
+  -X POST "https://api.buildkite.com/v2/packages/organizations/#{org.slug}/registries" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "name": "my registry",
+    "ecosystem": "ruby"
+    }' 
+```
+
+```json
+{
+  "id": "0191df84-85e4-77aa-83ba-6579084728eb",
+  "graphql_id": "UmVnaXN0cnktLS0wMTkxZGY4NC04NWU0LTc3YWEtODNiYS02NTc5MDg0NzI4ZWI=",
+  "slug": "my-registry",
+  "url": "https://api.buildkite.com/v2/packages/organizations/my-org/registries/my-registry",
+  "web_url": "https://buildkite.com/organizations/my-org/registries/my-registry",
+  "name": "my registry",
+  "ecosystem": "ruby",
+  "description": null,
+  "emoji": null,
+  "color": null,
+  "public": false,
+  "oidc_policy": null
+}
+```
+
+Required [request body properties](/docs/api#request-body-properties):
+
+<table class="responsive-table">
+<tbody>
+  <tr><th><code>name</code></th><td>Name of the new registry.<br><em>Example:</em> <code>"my registry"</code>.</td></tr>
+  <tr><th><code>ecosystem</code></th><td>Registry ecosystem based on the <a href="/docs/packages#get-started">package ecosystem</a> for the new registry.<br><em>Example:</em> <code>"ruby"</code>.</td></tr>
+</tbody>
+</table>
+
+Optional [request body properties](/docs/api#request-body-properties):
+
+<table class="responsive-table">
+  <tbody>
+    <tr><th><code>description</code></th><td>Description of the registry.<br><em>Default value:</em> <code>null</code>.</td></tr>
+  </tbody>
+</table>
+
+Required scope: `write_registries`
+
+Success response: `200 OK`
+
 ## List all registries
 
 Returns a list of an organization's registries.
@@ -21,7 +71,7 @@ curl -H "Authorization: Bearer $TOKEN" \
     "web_url": "https://buildkite.com/organizations/my-org/packages/registries/my-registry",
     "name": "my registry",
     "ecosystem": "ruby",
-    "description": "registry containing ruby gems",
+    "description": null,
     "emoji": null,
     "color": null,
     "public": false,