More review comments

src/cargo/util/config/key.rs

@@ -13,7 +13,7 @@ pub struct ConfigKey {
     // updated with `push` methods and looks like `CARGO_FOO_BAR` for pushing
     // `foo` and then `bar`.
     env: String,
-    // The current environment variable this configuration key maps to. This is
+    // The current toml key this configuration key maps to. This is
     // updated with `push` methods and looks like `foo.bar` for pushing
     // `foo` and then `bar`.
     config: String,

src/cargo/util/config/mod.rs

@@ -1473,7 +1473,7 @@ pub struct CargoBuildConfig {
 /// single string or a string list itself. For example these deserialize to
 /// equivalent values:
 ///
-/// ```
+/// ```toml
 /// a = 'a b c'
 /// b = ['a', 'b', 'c']
 /// ```