-We use the AST from libsyntax. We use libsyntax's visit module to walk the AST
-to find starting points for reformatting. Eventually, we should reformat everything
-and we shouldn't need the visit module. We keep track of the last formatted
-position in the code, and when we reformat the next piece of code we make sure
-to output the span for all the code in between (handled by missed_spans.rs).
+We use the AST from [syntex_syntax], an export of rustc's libsyntax. We use
+syntex_syntax's visit module to walk the AST to find starting points for
+reformatting. Eventually, we should reformat everything and we shouldn't need
+the visit module. We keep track of the last formatted position in the code, and
+when we reformat the next piece of code we make sure to output the span for all
+the code in between (handled by missed_spans.rs).
+
+[syntex_syntax]: https://crates.io/crates/syntex_syntax
+
+We read in formatting configuration from a `rustfmt.toml` file if there is one.
+The options and their defaults are defined in `config.rs`. A `Config` object is
+passed throughout the formatting code, and each formatting routine looks there
+for its configuration.