All examples' READMEs should contain a tutorial on running the example

[alexjpwalker]

I believe these are already written for the majority of examples. We should add any that don't exist already, and do a quality control pass over all of them. Each README should include:

• Introduction to, and summary of, the project
• Detailed tutorial on how to run it, typically consisting of:
  • Prerequisites
  • Load schema
  • Load data
  • Launch application (if applicable)
  • Querying