Replaced outdated doc

Author: ysimonson

clippy_lints/src/cargo_common_metadata.rs

@@ -7,7 +7,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//! lint on multiple versions of a crate being used
+//! lint on missing cargo common metadata
 
 use crate::rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
 use crate::rustc::{declare_tool_lint, lint_array};