"2. Create a directory for your local repository, and put the following text in a file called .gclient"

Why? The content is plain JavaScript, why is this a secret .name file instead of just gclient.js?

Because that's how glient works (the .glient is a configuration file for glient). If you want to use a different file name, please see the depot_tools documentation to see if it's possible to pass the file name of the configuration name as a parameter.