Suggestion: Add examples in README for basic use cases

[scouten-adobe]

From yong2023 via Discord:

I think it will be helpful to add in README on how to add credential to an image, then how to show the credentials.

I know this by asking my friends and try myself and finally using the command in Makefile and change the input image in it with my own. Something like:

"cargo run --example client ~/Desktop/Hepburn3.jpg target/tmp/client.jpg"

Then use make show or cargo run --example show -- target/tmp/client.jpg to show the credential

also can go to verify page at: https://verify.contentauthenticity.org/inspect to show the credentials added

[scouten-adobe]

@adobe export issue to Jira project CAI

[github-jira-sync-bot]

:white_check_mark: Jira issue https://jira.corp.adobe.com/browse/CAI-3861 is successfully created for this GitHub issue.