Typically you'd fork the project on GitHub, make a branch in your own fork, make the change, push the branch, and make a PR out of that.
In this case, it's a one character change so it's probably easier to just use the "Edit" button on GitHub, which does essentially that behind the scenes for you, all from the browser.
No particular permissions are necessary for either approach, other than having a GitHub account.
--Larry Garfield