HAR tutorial: Add Chrome section

[baltpeter]

Currently, our HAR files don't load in Chrome (tweaselORG/cyanoacrylate#45), which is why I am not going to add a Chrome section to the HAR tutorial I am creating as part of #7.

I also have a hotfix for that problem (tweaselORG/cyanoacrylate#47). When that is released, we can add a Chrome section, though that is not exactly high priority.

We should then also add a "common problems" item, explaining how to repair old HAR files.