bootstrap: document tidy

src/bootstrap/builder.rs

@@ -741,6 +741,7 @@ impl<'a> Builder<'a> {
                 doc::EmbeddedBook,
                 doc::EditionGuide,
                 doc::StyleGuide,
+                doc::Tidy,
             ),
             Kind::Dist => describe!(
                 dist::Docs,

src/bootstrap/doc.rs

@@ -882,6 +882,7 @@ tool_doc!(
         // "cargo-credential-wincred",
     ]
 );
+tool_doc!(Tidy, "tidy", "src/tools/tidy", ["tidy"]);
 
 #[derive(Ord, PartialOrd, Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct ErrorIndex {