Format files with dprint (#711)

The dprint formatter is a flexible system which will use sandboxed
WebAssembly formatters to format our code (mostly: it calls out to
`rustfmt` for Rust code).

A particularly interesting feature is that dprint can format Rust code
blocks in the Markdown files. However, before we turn that on, we need
to have a way to normalize the Markdown text as it is extracted[1].
That is so that the word put into the translations is kept after the
reformatting.

[1]: https://github.com/google/mdbook-i18n-helpers/issues/19

mdbook-exerciser/Cargo.toml

@@ -1,11 +1,11 @@
 [package]
 name = "mdbook-exerciser"
 version = "0.1.0"
+authors = ["Andrew Walbran <qwandor@google.com>"]
 edition = "2021"
 license = "Apache-2.0"
-authors = ["Andrew Walbran <qwandor@google.com>"]
-description = "A tool for extracting starter code for exercises from Markdown files."
 repository = "https://github.com/google/comprehensive-rust"
+description = "A tool for extracting starter code for exercises from Markdown files."
 
 [dependencies]
 anyhow = "1.0.68"

mdbook-exerciser/README.md

@@ -1,7 +1,7 @@
 # exerciser
 
-This is an mdBook renderer to generate templates for exercises from the Markdown source. Given a
-Markdown file `example.md` with one or more sections like:
+This is an mdBook renderer to generate templates for exercises from the Markdown
+source. Given a Markdown file `example.md` with one or more sections like:
 
 ````markdown
 <!-- File src/main.rs -->
@@ -22,5 +22,6 @@ and mdbook configuration in `book.toml` like:
 output-directory = "comprehensive-rust-exercises"
 ```
 
-It will create a file `book/exerciser/comprehensive-rust-exercises/example/src/main.rs` with the
+It will create a file
+`book/exerciser/comprehensive-rust-exercises/example/src/main.rs` with the
 appropriate contents.