Fix third_party/NotoSansCJK/README.pdfium.

- Add a "Security Critical" entry.
- Fix a typo.
- Add the fontTools version which was used for generating the font
  subset.

Change-Id: I0206de2ea38753f4c51add4bfad8ef9d47147e94
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/79537
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Hui Yingst <nigi@chromium.org>
diff --git a/third_party/NotoSansCJK/README.pdfium b/third_party/NotoSansCJK/README.pdfium
index c1de98e..80b1d09 100644
--- a/third_party/NotoSansCJK/README.pdfium
+++ b/third_party/NotoSansCJK/README.pdfium
@@ -3,9 +3,10 @@
 Version: Noto Sans CJK V2.001
 License: SIL Open Font License v1.1
 License File: LICENSE
+Security Critical: no
 
 Description:
-NotoSansSC-Regular.subset.otf constains a subset of NotoSansSC-Regular font.
+NotoSansSC-Regular.subset.otf contains a subset of NotoSansSC-Regular font.
 This font file is used for the test FPDFEditEmbedderTest.EmbedNotoSansSCFont,
 and it is included as a real-world example for testing PDFium's API to embed a
 CJK font into a PDF file, which contains multiple unicodes mapped to the same
@@ -19,4 +20,4 @@
 U+0000F906,U+000053E5,U+00008FD9,U+0000662F,U+00007B2C,U+00004E00,U+00003002, \
 U+00004E8C,U+00002F00,U+00002F06"
 
-where pyftsubset comes from https://github.com/behdad/fonttools
+where pyftsubset comes from https://github.com/behdad/fonttools (version 4.16.1).