fix CLAUDE instructions

Author: MangelMaxime

CLAUDE.md

@@ -19,7 +19,7 @@ The build system is implemented in F# at `src/Fable.Build/`. All commands go thr
 # Run tests (targets: javascript, typescript, python, dart, rust, beam, integration)
 ./build.sh test javascript
 ./build.sh test javascript --watch                # Watch mode (recompile on changes)
-./build.sh test javascript --skip-fable-library   # Skip fable-library rebuild (only if fable-library source is unchanged)
+./build.sh test javascript --force-fable-library  # Force fable-library rebuild (needed if you modified Fable compiler to fix the generation of `src/fable-library-*/**/*.fs` files)
 
 # Python-specific options
 ./build.sh test python --skip-fable-library-core  # Skip slow Rust extension + .pyi rebuild (Python only)