Power BI Query Editor – Inserting Rows to the Bottom of a Table

I have a table that looks like this in Power BI:

CourseID      Course
1             Math
2             Cooking
3             English
4             Spanish

I want to insert a row at the bottom that looks like this:

-1            null

I looked at the Microsoft Documentation, but it's not very helpful. Any suggestions?

Read more here: https://stackoverflow.com/questions/65714663/power-bi-query-editor-inserting-rows-to-the-bottom-of-a-table