Session concurrency User Guide edit

The User Guide is just source code in the main repo. Visit the repo (https://github.com/codeigniter4/CodeIgniter4) and you’ll find a folder “user_guide_src” with all the text. Submitting a Pull Request to change this would be very helpful. If you’ve never done a PR before, don’t be scared! I recommend people try it through GitHub first - navigate to the file you want to change and choose “Edit”. GitHub will walk you through making a fork, committing your changes, and then creating a Pull Request back to the main repo.