X icon doesn't work as ligature
**Describe the bug**

`<i class="ph">x</i>` doesn't show the cross icon because the ligature doesn't work. Not very strange, since it's a one-character description and therefore can't be a ligature. I suggest renaming it to something with at least two characters so this can be resolved, e.g. `cross`

**Steps to Reproduce**

Create a html-file, include phosphor icons in the `<head>` tag and use `<i class="ph">x</i>`

**Expected behavior**

The x icon should show

**Additional notes**

The workaround is to use `<i class="ph">&#xE4f6;</i>` instead, but that's not very user friendly and also not very clear from the documentation.