docs: hydra update oauth2-client updates only provided fields

The hydra update oauth2-client and ory update oauth2-client commands now
send a partial update built from the flags that were set, instead of
replacing the entire client. Update the CLI reference synopses and the
OAuth2 clients guide accordingly: the flag-based examples move to the
patch section, and the update (replace) section documents --file.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: alnr

docs/cli/ory-update-oauth2-client.md

@@ -15,7 +15,9 @@ Update an OAuth 2.0 Client
 
 ### Synopsis
 
-This command replaces an OAuth 2.0 Client by its ID. Please be aware that this command replaces the entire client. If only the name flag (-n "my updated app") is provided, the all other fields are updated to their default values.
+This command updates an OAuth 2.0 Client by its ID. Only the fields provided as flags are changed; all other fields keep their current values.
+
+To replace the entire client with a new configuration, use the --file flag. Fields missing from the file are reset to their default values.
 
 ```
 ory update oauth2-client [id] [flags]

docs/hydra/guides/oauth2-clients.mdx

@@ -142,15 +142,17 @@ If you use secret rotation, setting a new secret through the update client API c
 </TabItem>
 <TabItem value="cli" label="Ory CLI">
 
+To replace the entire client, pass a complete client definition from a file. Fields missing from the file are reset to their
+default values:
+
 ```
 ory update oauth2-client --project <project-id> --workspace <workspace-id> {client.id} \
-  --grant-type authorization_code --grant-type refresh_token  --grant-type client_credentials \
-  --response-type code \
-  --scope openid --scope offline_access \
-  --token-endpoint-auth-method client_secret_post \
-  --redirect-uri https://a-new-callback
+  --file client.json
 ```
 
+To change individual fields without touching the rest of the configuration, pass them as flags instead. See
+[Patch OAuth2 client](#patch-oauth2-client).
+
 </TabItem>
 <TabItem value="sdk" label="Ory SDK">
 
@@ -188,6 +190,17 @@ If you use secret rotation, setting a new secret through the patch client API cl
 3. Click on the **pen symbol** to update the client's configuration.
 3. When you are finished, scroll to the top and click **Save**.
 
+</TabItem>
+<TabItem value="cli" label="Ory CLI">
+
+Pass only the fields you want to change as flags. All other fields keep their current values:
+
+```
+ory update oauth2-client --project <project-id> --workspace <workspace-id> {client.id} \
+  --scope openid --scope offline_access \
+  --redirect-uri https://a-new-callback
+```
+
 </TabItem>
 <TabItem value="sdk" label="Ory SDK">