Where to include text notes in R package directory structure?

I authored an R package which has currently the following directory structure:

.git 
.Rproj.user 
docs 
inst 
man 
Meta 
R 
tests 
vignettes

I keep the package code on the GitHub repository. I want to add a note in a form of TXT file which will contain some package-relevant information (pseudo code of the main package algorithm). I want to add it to the package so as it can be accessed from the package's GitHub repository.

What is the best location in the files to add it so as the package check does not throw a message that there is some redundant file hanging?