doc: add compiler references

Author: gengjiawen

README.md

@@ -21,4 +21,9 @@ There is a book about learning how to make an interpreter: [Writing An Interpret
 ```bash
 $ cargo build
 $ cargo test
-```
+```
+
+## References on compiler
+* https://github.com/dinfuehr/dora
+* https://github.com/wren-lang/wren
+* https://github.com/apollographql/federation