Fixed non-escaped *s in grammar

[brauliobz]

Those break mbook's parsing sometimes.

[Havvy]

How do these break mdbook's parsing? Is it a Mardown thing, or an issue in mdbook?

[brauliobz]

@Havvy an example:

Text 1

> Text 2 <sup>*</sup> Text 3  
> Text 4  

Text 5

> Text 6 <sup>*</sup> Text 7  
> Text 8  

Text 9

is rendered by mdbook as:

Text 1

Text 2 Text 3
Text 4 Text 7
Text 8

Text 9

Notice the missing Text 5 and Text 6, and the italicized Text 3 and Text 4.
The github markdown engine renders it correctly:

Text 1

Text 2 ^* Text 3
Text 4

Text 5

Text 6 ^* Text 7
Text 8

Text 9

[matthewjasper]

@brauliobz, can you rebase so that this can be merged, unless @Havvy has any objections.

[brauliobz]

@matthewjasper Done.

[matthewjasper]

Thanks!