Add comprehensive BNF README and Support Packages section to main README

Co-authored-by: hzhangxyz <[email protected]>

Author: Copilot

README.md

@@ -344,6 +344,45 @@ Example programs are provided in the `examples/` directory:
 
 Each example demonstrates logical inference using propositional logic axioms.
 
+## Support Packages
+
+The DS project includes additional support packages that extend functionality:
+
+### BNF Conversion Library
+
+Located in the `/bnf` directory, this package provides bidirectional conversion between DS syntax formats:
+
+- **apyds-bnf** (Python): [PyPI](https://pypi.org/project/apyds-bnf/)
+- **atsds-bnf** (JavaScript): [npm](https://www.npmjs.com/package/atsds-bnf)
+
+The BNF library converts between:
+- **Ds format**: S-expression (lisp-like) syntax used internally by DS
+- **Dsp format**: Traditional, human-readable syntax with infix operators
+
+This makes it easier to write logical rules in a natural mathematical notation and convert them to/from the DS internal format.
+
+**Installation:**
+```bash
+# Python
+pip install apyds-bnf
+
+# JavaScript
+npm install atsds-bnf
+```
+
+**Quick example:**
+```python
+from apyds_bnf import parse, unparse
+
+# Convert readable syntax to DS format
+parse("a, b -> c")  # Returns: "a\nb\n----\nc"
+
+# Convert DS format to readable syntax
+unparse("a\nb\n----\nc")  # Returns: "a, b -> c"
+```
+
+For more details, see the [BNF package README](/bnf/README.md).
+
 ## Development
 
 ### Code Formatting