README still specifies that "a sample file will be used" in Docker example

[machawk1]

This is no longer the case and causes the error (as follows) when the instructed command is run:

ERROR: An index file must be specified if not piping, e.g.,
> ipwb replay /path/to/your/index.cdxj

usage: ipwb replay [-h] [-P [<host:port>]] [index]

Start the ipwb relay system

positional arguments:
  index                 path, URI, or multihash of file to use for replay

optional arguments:
  -h, --help            show this help message and exit
  -P [<host:port>], --proxy [<host:port>]
                        Proxy URL

[machawk1]

The README currently states:

A pre-built Docker image is made available that can be run as following:

$ docker container run -it --rm -p 5000:5000 oduwsdl/ipwb
The container will run an IPFS daemon, index a sample WARC file, and replay it using the newly created index. It will take a few seconds to be ready, then the replay will be accessible at http://localhost:5000/ with a sample archived page.

To index and replay your own WARC file, bind mount your data folders inside...

Per this issue (#504), a sample file is no longer used by default, so the README should be updated to reflect the state of the code.

@ibnesayeed Instead of removing this fundamental ipwb-with-docker usage, what are your thoughts for providing the command with an existing WARC file (from the repo, within the container) instead of giving an example that requires the additional steps just to get up-and-running.

Some other relevant projects (e.g., various webrecorder repos) provide a WARC of the IIPC homepage. I think having sample usage with real (provided) data would be better than the sample immediately requesting more steps just to get up-and-running.