feat: Final edits before handover to LF Training

[SensibleWood]

User Story

As a student of OpenAPI
I want the course delivered in a structured format
So I can have training delivered in a metered way
And demonstrate to others I have completed the course

Detailed Requirement

This is the final edit before course content is handed over to LF Training for delivery in structured format.

Changes required:

• Rename "Module" to "Chapter" throughout
• Revisit Chapter 1 and 2 and restructure based on standardized chapter format
• Completion of Chapter 3 README
• Anything else that is amiss...

[SensibleWood]

Reopened as work not done and fix to contributing guide required (and wanted to channel all PRs through this issue for final edits)