fix: Add dockerContextDir property to actor.json docs (#647)

Closes #638.

sources/platform/actors/development/actor_definition/actor_json.md

@@ -65,8 +65,9 @@ import TabItem from '@theme/TabItem';
 | `name`                 | Required | Name of the Actor. |
 | `version`              | Required | Actor version in the form `[Number].[Number]`, i.e. for example `0.0`, `0.1`, `2.3`, ... |
 | `buildTag`             | Optional | The tag name applied for the successful build of the Actor. Defaults to `latest`. For more information see the [builds](../builds_and_runs/builds.md) section. |
-| `environmentVariables` | Optional | An map of environment variables used during the local development that will be also applied to Actor at Apify platform. For more see the [environment variables](/cli/docs/vars) section of Apify CLI documentation. |
+| `environmentVariables` | Optional | A map of environment variables used during the local development that will be also applied to Actor at Apify platform. For more see the [environment variables](/cli/docs/vars) section of Apify CLI documentation. |
 | `dockerFile`           | Optional | If you specify the path to your Docker file under the `dockerfile` field, this file will be used for actor builds on the platform. If not specified, the system will look for Docker files at `.actor/Dockerfile` and `Dockerfile`, in this order of preference. For more see the [Dockerfile](./dockerfile.md) section. |
+| `dockerContextDir`     | Optional | Specifies the path to the directory used as the Docker context when building the Actor. The path is relative to the location of the `actor.json` file. Useful for having a monorepo with multiple Actors. See [Actor monorepos](../deployment/source_types.md#actor-monorepos) for more details. |
 | `readme`               | Optional | If you specify the path to your README file under the `readme` field, the README at this path will be used on the platform. If not specified, README at `.actor/README.md` or `README.md` will be used, in this order of preference. See our [Apify Academy article on writing a quality README files](/academy/get-most-of-actors/actor-readme). |
 | `input`                | Optional | You can embed your [input schema](./input_schema/index.md) object directly in `actor.json` under the `input` field. Alternatively, you can provide a path to a custom input schema. If not provided, the input schema at `.actor/INPUT_SCHEMA.json` or `INPUT_SCHEMA.json` is used, in this order of preference. |
 `storages.dataset`       | Optional | You can define the schema of the items in your dataset under the `storages.dataset` field. This can be either an embedded object or a path to a JSON schema file. [Read more](./output_schema.md#specification-version-1) about Actor output schemas. |