Add AZURE_ENV_FOUNDRY_PROJECT_ID in CustomizingAzdParameters.md file

Author: NirajC-Microsoft

docs/CustomizingAzdParameters.md

@@ -13,6 +13,7 @@ By default this template will use the environment name as the prefix to prevent
 | `AZURE_ENV_OPENAI_LOCATION`     | string | `swedencentral`   | Specifies the region for OpenAI resource deployment.                                                |
 | `AZURE_ENV_MODEL_DEPLOYMENT_TYPE` | string | `GlobalStandard` | Defines the deployment type for the AI model (e.g., Standard, GlobalStandard).                     |
 | `AZURE_ENV_MODEL_NAME`          | string | `gpt-4o`          | Specifies the name of the GPT model to be deployed.                                                |
+| `AZURE_ENV_FOUNDRY_PROJECT_ID`          | string | `<Existing Workspace Id>`          | Set this if you want to reuse an AI Foundry Project instead of creating a new one.                                                |                        
 | `AZURE_ENV_MODEL_VERSION`       | string | `2024-08-06`      | Version of the GPT model to be used for deployment.                                                |
 | `AZURE_ENV_IMAGETAG`            | string | `latest`          | Docker image tag used for container deployments.                                                   |
 | `AZURE_ENV_ENABLE_TELEMETRY`    | bool   | `true`            | Enables telemetry for monitoring and diagnostics.                                                  |