You should probably move the whole report off the README.md. And the report should also use bibliography. If you use RStudio and create an RMarkdown file, you can add bibliography. So
Start to compile used bibliography into a .bib file.
Move the report off README.md. REally the best thing would be to use LaTeX and the "official" templates if you're familiar with them. If not, you'll still have to add the preliminaries anyway.
Use RStudio and a .Rmd file which will give you the capability to insert bibliography in the file, and easily generate PDF files.
You should probably move the whole report off the README.md. And the report should also use bibliography. If you use RStudio and create an RMarkdown file, you can add bibliography. So