(cli, api definitions) Document fern api update, make small adjustments to OpenAPI automation page (#879)

Author: devalog

fern/products/api-def/openapi-pages/automation.mdx

@@ -8,7 +8,8 @@ Automatically pull your latest OpenAPI spec from a publicly available URL into y
 ## Setup
 <Steps>
   <Step title="Configure the origin URL">
-   Add the origin field to your generators.yml to specify where your OpenAPI spec is hosted:
+   Add the `origin` field to your `generators.yml` to specify where your OpenAPI spec is hosted:
+   
    ```yml title="generators.yml"
     api:
       specs: 
@@ -18,8 +19,9 @@ Automatically pull your latest OpenAPI spec from a publicly available URL into y
     ```
   </Step>
   <Step title="Add the GitHub Action">
-    Create `.github/workflows/sync-openapi.yml` in your repository:
-    ```yml
+    Create `.github/workflows/sync-openapi.yml` in your repository. This action uses [`fern api update`](/cli-api-reference/cli-reference/commands#fern-api-update) to pull the latest version of your OpenAPI spec from the `origin` field in your `generators.yml` file. 
+
+    ```yml title=".github/workflows/sync-openapi.yml"
     name: Sync OpenAPI Specs # can be customized
     on:                               # additional custom triggers can be configured
       workflow_dispatch:              # Manual trigger
@@ -57,4 +59,4 @@ This creates daily pull requests with any API spec updates. To change the freque
 
 ## Other use cases 
 
-If your OpenAPI spec lives in a different repository (rather than at a public URL), you can sync it to your Fern folder using cross-repository sync. See the [sync-openapi GitHub Action README](https://github.com/fern-api/sync-openapi) for this and other advanced configurations. 
+If your OpenAPI spec lives in a different repository (rather than at a public URL), you can sync it to your Fern folder using explicit file mappings. See the [sync-openapi GitHub Action README](https://github.com/fern-api/sync-openapi) for this and other advanced configurations. 

fern/products/cli-api-reference/pages/commands.mdx

@@ -13,6 +13,7 @@ hideOnThisPage: true
 | [`fern login`](#fern-login) | Login to Fern CLI via GitHub or Google |
 | [`fern logout`](#fern-logout) | Log out of the Fern CLI |
 | [`fern export`](#fern-export) | Export an OpenAPI spec for your API |
+| [`fern api update`](#fern-api-update) | Manually update your OpenAPI spec |
 
 ## Documentation Commands
 
@@ -566,4 +567,24 @@ hideOnThisPage: true
      Use `--include-major` to include major version upgrades. Major versions are skipped by default to prevent breaking changes.
 
   </Accordion>
+  <Accordion title="fern api update">
+  Pulls the latest OpenAPI spec from the specified `origin` in `generators.yml` and
+  updates the local spec. Alternatively, you can [automate this process by setting up a GitHub Action](/api-definitions/openapi/sync-your-open-api-specification).
+
+  <CodeBlock title="terminal">
+    ```bash
+    fern api update [--api <api>]
+    ```
+  </CodeBlock>
+
+  ### api
+
+  Use `--api` to specify the API to update if there are multiple specs with a defined `origin` in `generators.yml`. If you don't specify an API, all OpenAPI specs with an `origin` will be updated. 
+
+  <CodeBlock title="terminal">
+    ```bash
+    fern api update --api public-api
+    ```
+  </CodeBlock>
+  </Accordion>
 </AccordionGroup>

fern/products/sdks/reference/generators-yml-reference.mdx

@@ -195,7 +195,7 @@ api:
 </ParamField>
 
 <ParamField path="origin" type="string" toc={true}>
-  URL of the API definition origin for polling updates.
+  URL of the API definition origin for pulling updates.
 </ParamField>
 
 <ParamField path="overrides" type="string" toc={true}>

fern/snippets/openapi-specs.mdx

@@ -22,7 +22,7 @@ api:
 </ParamField>
 
 <ParamField path="origin" type="string" toc={true}>
-  URL of the API definition origin for polling updates.
+  URL of the API definition origin for pulling updates. For instructions on how to set up automatic syncing, refer to [Sync your OpenAPI specification](/learn/api-definitions/openapi/sync-your-open-api-specification).
 </ParamField>
 
 <ParamField path="overrides" type="string" toc={true}>