To edit the Project landing page in Azure DevOps, follow the below steps

Step 1: Go to the Project

Step 2: Click on the edit button at the top as shown

Step 3: As soon as you click on the edit button, you will get popup like this as shown below.In the popup you can either write your own description and you can also set a read me page to a Wiki

Step 4: Once you have done any of the changes,click on the “Save” button

Step 5: Once it’s saved, you can see new description as shown below