Add hint to word limit in abstract

[stachch]

The Word template states:

Abstract: This is a brief overview of the paper, which should be 70 to 150 words long and include the most relevant points

Further, @heseba required a single paragraph in the abstract which seems to be a general guideline.

[sieversMartin]

So, you want me to add a small text to the template?

[koppor]

Yes, I think https://github.com/gi-ev/LNI/blob/master/lni-author-template.tex#L32 would be the place to be. Just pasting a modified version of the text:

This is a brief overview of the paper, which should be 70 to 150 words long and include the most relevant points. This has to be a single paragraph.

[sieversMartin]

Done.