fix: add docs.rs badge + cookbook link per §2.2 (Refs PMAT-149)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: noahgift

README.md

@@ -12,6 +12,7 @@
 
 [![CI](https://github.com/paiml/forjar/actions/workflows/ci.yml/badge.svg)](https://github.com/paiml/forjar/actions/workflows/ci.yml)
 [![crates.io](https://img.shields.io/crates/v/forjar.svg)](https://crates.io/crates/forjar)
+[![Documentation](https://docs.rs/forjar/badge.svg)](https://docs.rs/forjar)
 [![MSRV](https://img.shields.io/badge/MSRV-1.88.0-blue)](https://blog.rust-lang.org/)
 
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