Each Sprint has a "Sprint Forecast" email that details what will be worked on during this Sprint.
At the end of the Sprint, this should be replied to with a "Sprint Review" email that shows a breakdown of what was completed.
If you're using GitHub to manage your project, create repeatable templates that can easily edited and emailed out. See GitHub Issues - Do you create a template for your Sprint Reviews, Retros and Forecasts? for more details.
Each Sprint has the following stages: