Make a backup of the project's documents

[pedroLBatista]

Use an External HDD to backup all the files related to the project

[SirPolaris]

@pedroLBatista though GitHub you can upload your documents via /docs/ folder or something of the like. GitHub will protect and record all the history of your work.

Unless formatting is important, aim for plain text or markdown .md files.

If the documents are informational, make them into wiki pages for your future reference, or people that come after you :)