Merge branch 'feature/298-explain_s3_is_necessary_in_readme' into 'develop'

Edited README.md to make clear that a working S3 object-store is necessary

See merge request !272

README.md

@@ -13,6 +13,9 @@ Open a console and try running `docker -h` and `docker-compose -h` to verify the
 Create the environment file `.env`. You can start by copying the template file [.env.template.development](https://gitlab.ruhr-uni-bochum.de/researchdata/rdms/-/blob/master/.env.template.development) to `.env` and customizing the values to your setup. <br>
 Note: For production environment, use .env.template as your template.
 
+Note: Currently it is **necessary** to provide a working S3-interfaced object-store for RDMS to function. Therefore, in your `.env` file you will need to check the _S3 settings_ section and ensure that the properties in this section have valid values (including that `USE_S3` is set to `true`).
+
+
 ## Quick start
 If you would like to do a test run of the system, start the docker containers
 ```bash