README: note we have both python and shell implementations

Author: bluca

README.md

@@ -9,8 +9,18 @@ metadata about the package for which the binary was compiled.
 See [Package Metadata for Core Files](https://systemd.io/COREDUMP_PACKAGE_METADATA/)
 for the overview and details.
 
+We provide implementations in Python and POSIX shell, with compatible CLI
+interfaces.
+
 ## Requirements
 
+### generate-package-notes.py
+
 * python3 (>= 3.5)
 * python3-simplejson
-* binutils (>= 2.38)
+* binutils (>= 2.38) [--readonly true]
+
+### generate-package-notes.sh
+
+* POSIX shell
+* binutils (>= 2.38) [--readonly true]