[NTG-context] last bookmark is wrong

[Taco Hoekwater]

Peter Münster wrote:
> Hello,
> 
> The last bookmark is s3 instead of b3 (MKII and MKIV):
> 
> \setupinteraction[state=start]
> \placebookmarks[section]
> \starttext
> \section{s1}\bookmark{b1}
> \section{s2}\bookmark{b2}
> \section{s3}\bookmark{b3}
> \stoptext

That is because there is no text at all following the last bookmark,
so hopefully this buglet will not affect any finished documents.

Best wishes,
Taco