make sentence more simple

compiler/rustc_codegen_llvm/src/mono_item.rs

@@ -111,7 +111,7 @@ fn add_aliases(&self, aliasee: &llvm::Value, aliases: &[(DefId, Linkage, Visibil
         }
     }
 
-    /// Whether a definition or declaration can be assumed to be local to a group of
+    /// A definition or declaration can be assumed to be local to a group of
     /// libraries that form a single DSO or executable.
     /// Marks the local as DSO if so.
     pub(crate) fn assume_dso_local(&self, llval: &llvm::Value, is_declaration: bool) -> bool {