add links to monkey and to the book

index.md

@@ -2,7 +2,7 @@
 
 Go Repl Open Language is a small interpreted (for now) language implemented in Go.
 
-Initially loosely based on Monkey from the Writing an Interpret in Go book but fully re designed and reimplemented since.
+Initially loosely based on [Monkey](https://monkeylang.org/) from the Writing an Interpreter in Go [book](https://interpreterbook.com) but fully re designed and reimplemented since.
 See more on [github](https://github.com/grol-io/grol/). Or try the `wasm` version right below
 (and we also have a [discord bot](https://github.com/grol-io/grol-discord-bot#grol-discord-bot)).