Add Document Export Functionality

[devleejb]

What would you like to be added:
Currently, users can write Markdown documents in CodePair, but there is no functionality to export these documents to formats like PDF. It would be beneficial to introduce a document export feature that allows users to save their Markdown documents in various file formats.

Why is this needed:
Adding a document export functionality will enhance the usability of CodePair and provide users with the flexibility to save and share their work in different formats. This feature can improve the overall user experience and make it easier for users to collaborate and share their work outside of the platform.

Additional Information: