Improve comments.

Author: ywxt

rustfmt.toml

@@ -18,7 +18,7 @@ ignore = [
     "/tests/crashes/",                # Many of these tests contain syntax errors.
     "/tests/debuginfo/",              # These tests are somewhat sensitive to source code layout.
     "/tests/incremental/",            # These tests are somewhat sensitive to source code layout.
-    "/tests/parallel/",               # Some have syntax errors.
+    "/tests/parallel/",               # These tests contain syntax errors.
     "/tests/pretty/",                 # These tests are very sensitive to source code layout.
     "/tests/run-make/export",         # These tests contain syntax errors.
     "/tests/run-make/translation/test.rs", # This test contains syntax errors.