chore(README): add batch plugin to the builtin list (#568)

Signed-off-by: iisteev <isteevan.shetoo@is-info.fr>

Author: iisteev

README.md

@@ -546,6 +546,7 @@ Browse [builtin actions](./pkg/plugins/builtin)
 | **`echo`**     | Print out a pre-determined result                                                                                                                                                                                                                 | [Access plugin doc](./pkg/plugins/builtin/echo/README.md)     |
 | **`http`**     | Make an http request                                                                                                                                                                                                                              | [Access plugin doc](./pkg/plugins/builtin/http/README.md)     |
 | **`subtask`**  | Spawn a new task on µTask                                                                                                                                                                                                                         | [Access plugin doc](./pkg/plugins/builtin/subtask/README.md)  |
+| **`batch`**    | Spawn a batch of tasks on µTask                                                                                                                                                                                                                   | [Access plugin doc](./pkg/plugins/builtin/batch/README.md)    |
 | **`notify`**   | Dispatch a notification over a registered channel                                                                                                                                                                                                 | [Access plugin doc](./pkg/plugins/builtin/notify/README.md)   |
 | **`apiovh`**   | Make a signed call on OVH's public API (requires credentials retrieved from configstore, containing the fields `endpoint`, `appKey`, `appSecret`, `consumerKey`, more info [here](https://docs.ovh.com/gb/en/customer/first-steps-with-ovh-api/)) | [Access plugin doc](./pkg/plugins/builtin/apiovh/README.md)   |
 | **`ssh`**      | Connect to a remote system and run commands on it                                                                                                                                                                                                 | [Access plugin doc](./pkg/plugins/builtin/ssh/README.md)      |