Added missing sentence about inactivity

Author: jackdomleo7

CONTRIBUTING.md

@@ -4,7 +4,7 @@ When contributing to this repository, please first discuss the change you wish t
 
 When looking to contribute to Checka11y.css, please first look at the [Checka11y.css Kanban Board](https://github.com/jackdomleo7/Checka11y.css/projects/3). Any issue sitting in the "To do (approved)" column is available to anyone to be picked up and worked on. _Do not pick up any issues in the "Backlog" column since these have not yet been approved to be added to the Checka11y.css project._ Once you have found an issue you would like to work on, comment on issues asking if you can pick it up. Please do not ask to work on an issue that is assigned to someone else (you can see who is assigned to an issue by looking at the "assignee").
 
-You cannot be assigned to more than one issue at the same time, unless you are an owner/collaborator or have had permission from an owner/collaborator. Please complete the issue you are working on before requesting to be assigned to another issue. This is to allow fair opportunity to those wanting to contribute. If you are assigned to an issue, but no longer want to be
+You cannot be assigned to more than one issue at the same time, unless you are an owner/collaborator or have had permission from an owner/collaborator. Please complete the issue you are working on before requesting to be assigned to another issue. This is to allow fair opportunity to those wanting to contribute. If you are assigned to an issue, but no longer want to be, just add a comment on the issue letting us know you want to be unassigned (no questions asked). You will automatically be unassigned from an issue after 3 months of inactivity.
 
 This project is happy to take part in [Hacktoberfest](https://hacktoberfest.digitalocean.com) each year and is willing to help dedicated developers make contributions to qualify for their Hacktoberfest profile. We will automatically add the `Hacktoberfest` tag to any pull request in the month of October, unless we feel the pull request is spam, in which case we will mark the pull request as `spam` and the pull request will be closed meaning it will not qualify as a valid pull request for the Hacktoberfest event.