Document "Define a new schema specification" unclear for docker usage

[th0ger]

When running in kafa-connect-datagen in Docker and specifying "schema.filename": "/path/to/your_schema.avsc", using the "the absolute path" as documented in Define a new schema specification, I get the following error:

{"error_code":400,"message":"Connector configuration is invalid and contains the following 1 error(s):
Unable to find the schema file

First, the error is not searchable in github issues, because it was only pasted as a screenshot in #22 (comment) (@elabbassiwidad). (Hence repeating it here.)
Second, the solution is burried deep in the comments #22 (comment) (@C0urante):

You must copy the schema file onto the docker container you're running, at the path used for the schema.filename property in the connector config.

Example: With local schema file in $PWD/my_schema.avsc

datagen-config.json:
---
schema.filename": "/tmp/schemas/my_schema.avsc

docker-compose.yml:
---
  connect:
    image: localimage/kafka-connect-datagen:latest
    build:
      context: .
      dockerfile: Dockerfile
    ...
    volumes:
      - type: bind
        source: .
        target: /tmp/schemas

I suggest to clarify the README, since "the absolute path" is a quite misleading for docker users.