Hidden code in knowls printing in download.

[jenpaulhus]

@rvisser7 and I were looking at downloads and noted that if a knowl has a hidden "note" in it, that note gets printed in the downloaded file.

For example in ECNF download of searches (even currently on production) in the middle of the file, it says

> 
> //Base field (field_label) --
> //    A {{DEFINES("number field", wikipedia="Algebraic_number_field", mathlib="NumberTheory/NumberField/\
Basic.html#NumberField")}} is a finite degree field extension of the field $\Q$ of rational numbers. In LM\
FDB, number fields are identified by a label.
> 
> //    {# Note:  I left out the knowl for degree here, since it is technically defining the degree of a n\
umber field, rather than a general field extension (which is suggested by this definition)... degree #}
> 

I don't think we want that "Note" at the bottom in the downloads. Is there a way to exclude hidden messages from printing to the download files?

Alternatively, maybe this is the only knowl with a hidden note and we can get rid of it. Here's the knowl:

https://beta.lmfdb.org/knowledge/show/nf