introduce --parallel to limit concurrent engine calls

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

docs/reference/compose.md

@@ -42,6 +42,7 @@ Docker Compose
 | `--compatibility` |  |  | Run compose in backward compatibility mode |
 | `--env-file` | `string` |  | Specify an alternate environment file. |
 | `-f`, `--file` | `stringArray` |  | Compose configuration files |
+| `--parallel` | `int` | `-1` | Control max parallelism, -1 for unlimited |
 | `--profile` | `stringArray` |  | Specify a profile to enable |
 | `--project-directory` | `string` |  | Specify an alternate working directory
 (default: the path of the, first specified, Compose file) |

docs/reference/docker_compose.yaml

@@ -208,6 +208,16 @@ options:
       experimentalcli: false
       kubernetes: false
       swarm: false
+    - option: parallel
+      value_type: int
+      default_value: "-1"
+      description: Control max parallelism, -1 for unlimited
+      deprecated: false
+      hidden: false
+      experimental: false
+      experimentalcli: false
+      kubernetes: false
+      swarm: false
     - option: profile
       value_type: stringArray
       default_value: '[]'