incoming/.gitkeep als Datei- statt Verzeichnismuster trackbar (schliesst #88)

Files changed:
- .gitignore
- CHANGES.md
- README.md
- VERSION
- incoming/.gitkeep
- instructions/bootstrap.md
- raw/CONTRACT.md
- tools/CONTRACT.md
- tools/chemenu/commands/docs_verify.py

raw/CONTRACT.md

@@ -63,8 +63,9 @@ walks `raw/` recursively and works unchanged either way.
 
 ## Getting a file in: `incoming/`
 
-`raw/` is never chosen by hand. A file to be ingested is dropped into the gitignored top-level
-`incoming/` - flat: no subdirectory carries any classification any more. A
+`raw/` is never chosen by hand. A file to be ingested is dropped into the top-level `incoming/`
+- gitignored content, so a fresh clone finds the directory itself already there but never
+anything dropped into it - flat: no subdirectory carries any classification any more. A
 subdirectory is still tolerated if one is used out of habit or by an older script (so an upgrade
 never has to touch a caller), but it is **ignored**, never inspected: