reformatting deprectation warning message

Author: hulxv

clang-tools-extra/include-cleaner/tool/IncludeCleaner.cpp

@@ -198,15 +198,15 @@ class Action : public clang::ASTFrontendAction {
 
     if (!Insert) {
       llvm::errs()
-          << "[WARNING] -insert is deprecated in favor of `-disable-insert`. "
+          << "warning: `-insert=0` is deprecated in favor of `-disable-insert`. "
              "The old flag was confusing since it suggested that inserts "
              "were disabled by default, when they were actually enabled. "
              "See https://github.com/llvm/llvm-project/issues/132983\n";
     }
 
     if (!Remove) {
       llvm::errs()
-          << "[WARNING] -remove is deprecated in favor of `-disable-remove`. "
+          << "warning: `-remove=0` is deprecated in favor of `-disable-remove`. "
              "The old flag was confusing since it suggested that removes "
              "were disabled by default, when they were actually enabled. "
              "See https://github.com/llvm/llvm-project/issues/132983\n";