Fixing small typo in README. Closes googleworkspace#8.

Author: Eric Koleda

simple_tasks/README.md

@@ -28,7 +28,7 @@ scratch, follow the steps below.
 1. Create a new standalone script in your Google Drive
    ([instructions available here](https://developers.google.com/apps-script/managing_projects#creatingDrive))
    and add in each of the files in this directory. You should already  have a
-   file named Code.gs in your project, and you can replace it's contents with
+   file named Code.gs in your project, and you can replace its contents with
    the new code. For the remaining files, ensure you select
    **File > New > Html file** when creating the files, and when entering the
    file name omit the .html suffix as it will be added automatically.