I've never understood why github shows the first line of the most recent commit for files / folders next to their name instead of the first line of any README.m

I've never understood why github shows the first line of the most recent commit for files / folders next to their name instead of the first line of any README.md file inside the folder. Even on projects that I'm actively working on, the most recent commit of a folder gives me no useful information, whereas if I could edit the README.md I could atleast add a description of each folder so that new users could understand the directory structure better.