Auto merge of #42936 - steveklabnik:update-mdbook, r=alexcrichton

update crate dependencies

I wanted to update mdbook's version. This ended up updating a bunch of other stuff too.

I am not sure if updating this much stuff is considered a Good Idea or not; happy to figure out how to make it smaller if someone can help me figure out how to use x.py to do it.

src/tools/rustbook/Cargo.toml

@@ -5,8 +5,8 @@ version = "0.1.0"
 license = "MIT/Apache-2.0"
 
 [dependencies]
-clap = "2.19.3"
+clap = "2.25.0"
 
 [dependencies.mdbook]
-version = "0.0.21"
+version = "0.0.22"
 default-features = false