Update link in README (#185)

* doc: change link in README
* doc: update link in tutorial

Author: IoannisNezis

README.md

@@ -6,7 +6,7 @@
 Rowan is a library for lossless syntax trees, inspired in part by
 Swift's [libsyntax](https://github.com/apple/swift/tree/5e2c815edfd758f9b1309ce07bfc01c4bc20ec23/lib/Syntax).
 
-A conceptual overview is available in the [rust-analyzer repo](https://github.com/rust-analyzer/rust-analyzer/blob/master/docs/dev/syntax.md).
+A conceptual overview is available in the [rust-analyzer book](https://rust-analyzer.github.io/book/contributing/syntax.html).
 
 See `examples/s_expressions` for a tutorial, and [rust-analyzer](https://github.com/rust-analyzer/rust-analyzer/) for real-world usage.
 

examples/s_expressions.rs

@@ -7,7 +7,7 @@
 //!
 //! It's suggested to read the conceptual overview of the design
 //! alongside this tutorial:
-//! https://github.com/rust-analyzer/rust-analyzer/blob/master/docs/dev/syntax.md
+//! https://rust-analyzer.github.io/book/contributing/syntax.html
 
 /// Let's start with defining all kinds of tokens and
 /// composite nodes.