Small Documentation Typo

[aaronaskew]

Found a small typo in this codelab's documentation.

On https://codelabs.developers.google.com/codelabs/apps-script-intro/#4, in the paragraph below this line of code:

var sheet = SpreadsheetApp.getActiveSheet();

The text and assigns to the value to the variable address. should be and assigns the value to the variable address..

I'd submit a PR, but I don't see the documentation in this repo.