Generate springdoc/springdoc-openapi's README.md from this repository

[codespearhead]

As noted in this PR, the README.md in the main repository is manually generated from AsciiDoc files in this repository.

This process should be automated via GitHub Actions to avoid them going out of sync.

• Add maven wrapper and README.md with instructions on how to build this repository #75
• Remove code duplication with AsciiDoc's Include Directive #73
• Continuous Delivery of README.md from this repository to the main repository via GitHub Actions #74

[bnasslahsen]

docs updated