Fix the link to the Gluon Book in README
@@ -281,7 +281,7 @@ nnoremap <silent> gd :call LanguageClient_textDocument_definition()<CR>
## Documentation
-[The Gluon Book](http://gluon-lang.org/book/introduction.html)
+[The Gluon Book](http://gluon-lang.org/book/index.html)
[Gluon Standard Library API Reference](http://gluon-lang.org/doc/nightly/std/index.html)
