Update keyword styling

This contains the proper style. The problem is, when applied to:

```
If you'll notice, all lines of that bullet list are tagged **Bullet [PACKT]**, except the last. It's tagged
**Bullet End [PACKT]**.
```
...it renders:
```xml
<text:p text:style-name="Normal_20__5b_PACKT_5d_">If you’ll notice, all lines of that bullet 
list are tagged <text:span text:style="Key_20_Word_205b_PACKT_5d_">Bullet [PACKT]</text:span>, 
except the last. It’s tagged <text:span text:style="Key_20_Word_205b_PACKT_5d_">Bullet 
End [PACKT]</text:span>.</text:p>
```
The double-underscore is trimmed out for some reason.

In another situation, it doesn't do that.

```
The output will be compacted XML (FODT), so it will be **hard** to read. That why running it through
`xmllint` is handy.
```
renders
```xml
      <text:p text:style-name="Normal_20__5b_PACKT_5d_">The output will be compacted XML 
(FODT), so it will be <text:span text:style="Key_20_Word_20__5b_PACKT_5d_">hard</text:span> 
to read. That why running it through xmllint is handy.</text:p>
```