Support Docusaurus 2.4.1 version to generate PDF

[sunilg27]

Hi,

This PR is raised to fix the issue in generating the PDF with Docusaurus v2.

• Command to generate PDF for Docusaurus 2.4.1 is updated in README file
• Docusaurus v2 beta is no longer supported, hence removed in README file
• Sample v241-docusaurus.pdf is also added to repository

Please feel free to make changes if necessary.