Update code examples.

[evanlally]

This PR Contains

• Minor spelling and indentation fixes
• Updates to the code examples to provide a better explanation of Web Credentials and the Credential Interface Query

Reminder: running this in development

https://jekyllrb.com/tutorials/using-jekyll-with-bundler/

1. Copy .localGemfile to Gemfile in the source directory
2. Run the jekyll server

   bundle exec jekyll serve

For Review:

• [ ] Technical review of code examples
• [ ] Relevant updates in chapi-example repos:
  • https://issuer.example.chapi.io/
  • https://wallet.example.chapi.io/
  • https://verifier.example.chapi.io/