Clean code guide : Markdown Version

[priyasingh199885]

1. Mermaid diagrams
2. .adoc --> .md Changes to package.json -- still working (can be discussed in upcoming call)

This PR is only to pre-view the changes and not necessarily be approved or merged.

[cla-assistant[bot]]

All committers have signed the CLA.

[priyasingh199885]

Nice progress! Some points to check:

• [ ] all abap-code-review/src/*.md files should be deleted because everything is contained in one single abap-code-review/ABAPCodeReview.md file
• [ ] markdown-linkcheck should be integrated in package.json scripts
• [ ] README.md and abap-code-review/README.md need to be adjusted to new files and build process

[priyasingh199885]

What are the changes needed in README.md? and abap-code-review/Readme.md too?

[xtough]

What are the changes needed in README.md? and abap-code-review/Readme.md too?

• Links to .adoc and .pdf need to be changed to the new ABAPCodeReview.md
• build process description for producing PDF needs to be removed / adapted to describe only markdown-linkcheck (once this is implemented)

[xtough]

build is currently failing:

npm ci can only install packages when your package.json and package-lock.json or npm-shrinkwrap.json are in sync. Please update your lock file with npm install before continuing.

That means you need to git add+commit+push either a package-lock.json or npm-shrinkwrap.json in your branch

[KlausHaeuptleSAP]

@priyasingh199885: Thanks! Great contribution!