discussion: best practices and resources helpful to increase quality of spoon

Propose
- List of IntelliJ IDEA code inspections (included in both free and commercial editions)
- List of software quality guidelines
- List of suggested books

No target file, documentation location, or acceptance criteria are named. Start by reviewing Spoon's existing documentation and the three proposed resource categories: IntelliJ IDEA inspections, software quality guidelines, and suggested books. Done means agreeing on the scope and adding curated, relevant resources in the project's chosen documentation location.

Written by the indexing model from the issue text.