Update README.md

Update automated deployment Blockscout section with an additional step for mac OS users.

README.md

@@ -162,17 +162,36 @@ cat group_vars/infrastructure.yml.example group_vars/all.yml.example > group_var
 
 1. Ensure all the [BlockScout prerequisites](#Prerequisites-for-deploying-blockscout) are installed and has the right version number;
 2. Merge `blockscout` and `all` config template files into single config file:
+
 ```bash
 cat group_vars/blockscout.yml.example group_vars/all.yml.example > group_vars/all.yml
 ```
 **Note!** All three configuration files are compatible to each other, so you can simply `cat group_vars/blockscout.yml.example >> group_vars/all.yml` if you already do have the `all.yml` file after the deploying of infrastructure.
+
 3. Set the variables at `group_vars/all.yml` config template file as described at the [corresponding part of instruction](#Configuration);
   **Note!** Use `chain_custom_environment` to update the variables in each deployment. Map each deployed chain with variables as they should appear at the Parameter Store. Check the example at `group_vars/blockscout.yml.example` config file. `chain_*` variables will be ignored during BlockScout software deployment.
-4. Run `ansible-playbook deploy_software.yml`; 
-5. When the prompt appears, check that server is running and there is no visual artifacts. The server will be launched at port 4000 at the same machine where you run the Ansible playbooks. If you face any errors you can either fix it or cancel the deployment by pressing **Ctrl+C** and then pressing **A** when additionally prompted.
-6. When server is ready to be deployed simply press enter and deployer will upload Blockscout to the appropriate S3.
-7. Two other prompts will appear to ensure your will on updating the Parameter Store variables and deploying the BlockScout through the CodeDeploy. Both **yes** and **true** will be interpreted as the confirmation.
-8. Monitor and manage your deployment at [CodeDeploy](https://console.aws.amazon.com/codesuite/codedeploy/applications) service page at AWS Console.
+  
+4. This step is for mac OS users. Please skip it, if this is not your case.
+
+To avoid the error
+```
+TASK [main_software : Fetch environment variables] ************************************
+objc[12816]: +[__NSPlaceholderDate initialize] may have been in progress in another thread when fork() was called.
+objc[12816]: +[__NSPlaceholderDate initialize] may have been in progress in another thread when fork() was called. We cannot safely call it or ignore it in the fork() child process. Crashing instead. Set a breakpoint on objc_initializeAfterForkError to debug.
+```
+error and crashing of Python follow the next steps:
+
+- Open terminal: `nano .bash_profile`;
+- Add the following line to the end of the file: `export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES`;
+- Save, exit, close terminal and re-open the terminal. Check to see that the environment variable is now set: `env`
+
+(source: https://stackoverflow.com/questions/50168647/multiprocessing-causes-python-to-crash-and-gives-an-error-may-have-been-in-progr);
+
+5. Run `ansible-playbook deploy_software.yml`; 
+6. When the prompt appears, check that server is running and there is no visual artifacts. The server will be launched at port 4000 at the same machine where you run the Ansible playbooks. If you face any errors you can either fix it or cancel the deployment by pressing **Ctrl+C** and then pressing **A** when additionally prompted.
+7. When server is ready to be deployed simply press enter and deployer will upload Blockscout to the appropriate S3.
+8. Two other prompts will appear to ensure your will on updating the Parameter Store variables and deploying the BlockScout through the CodeDeploy. Both **yes** and **true** will be interpreted as the confirmation.
+9. Monitor and manage your deployment at [CodeDeploy](https://console.aws.amazon.com/codesuite/codedeploy/applications) service page at AWS Console.
 
 # Destroying Provisioned Infrastructure
 
@@ -236,4 +255,4 @@ This is due to a bug in Terraform, however the fix is to just rerun `ansible-pla
 
 ### Server doesn't start during deployment
 
-Even if server is configured correctly, sometimes it may not bind the appropriate 4000 port due to unknown reason. If so, simply go to the appropriate nested blockscout folder, kill and rerun server. For example, you can use the following command: `pkill beam.smp && pkill node && sleep 10 && mix phx.server`.
+Even if server is configured correctly, sometimes it may not bind the appropriate 4000 port due to unknown reason. If so, simply go to the appropriate nested blockscout folder, kill and rerun server. For example, you can use the following command: `pkill beam.smp && pkill node && sleep 10 && mix phx.server`.