Add sample use cases via human readable examples

[machawk1]

The README gets into some of the technical details of the software but fails to describe a high-level use case. Having these sort of use cases might facilitate those that want to use the software without knowing the technical details to do so for their own use cases.

An example:

1. Alice has a collection of archives in the form of WARCs of her homepage on her system at /home/Alice/Documents/archive/. She wants to share these captures using ipwb. (Show a screenshot/GIF of her directory.)
2. She installs the software by typing pip install ipwb using the command-line then types ipwb index /home/Alice/Documents/archive/ > alice.cdxj to generate an index file of her WARCs.
3. Alice sends alice.cdxj to Carol using the method of her choosing. Carol downloads alice.cdxj to her system. (Screenshots of communication/email/etc.)
4. Carol installs ipwb by typing pip install ipwb on the command-line.
5. Carol then wants to access Alice's captures, so types ipwb replay alice.cdxj.
6. With the last command, ipwb said that the archive can be seen at the URL http://localhost:5000, so Carol opens her web browser and accesses this URL. (screenshot)

These can reside on the wiki (where some of the technical details currently on the README ought to reside), with some graphical representation of a basic case in the README to potentially spark interest.