Describe the bug
Table of Contents contains Cyrillic characters and during the PDF generation process I receive incorrect Table of contents (see screenshot).

To Reproduce

1. Create a Table of Contents with node names containing Cyrillic characters.
   

2. Follow the instructions to generate a PDF from the documentation.

3. Open PDF file and see Table of Contents.

Expected behavior
Table of Contents should display correctly with Cyrillic characters in PDF

Context (please complete the following information):

• OS: Windows
• Docfx version: [e.g. 2.75.3]