Tweak list_items() docstring

Use the first line as a high-level description. Separate the explanation
of the `items` argument type, and drop a stray '"' character.

Author: djc

src/cli/common.rs

@@ -378,11 +378,11 @@ where
     Ok(utils::ExitCode(0))
 }
 
-/// Iterates over pairs representing the name of a target or component and a
-/// boolean value indicating whether it is installed or not.
-/// The boolean value is needed to determine whether to print "(installed)"
-/// next to the target/component name."
-pub(super) fn list_items<'a>(
+/// Print a list of items (targets or components) to stdout.
+///
+/// `items` represents the list of items, with the name and a boolean
+/// to represent whether the item is currently installed.
+pub(super) fn list_items(
     items: impl Iterator<Item = (impl Display, bool)>,
     installed_only: bool,
     quiet: bool,