Remove comment and add new ambiguous example

[StevellM]

Follows #1664

We can remove the comment now, I have checked what was needed. I found another ambiguous example in my data, so I added it.
While playing with data, I found a misbehaving argument check which did not take in account the case of genus enumeration in the non full rank case for binary form over QQ.

[simonbrandhorst]

Thanks.

[thofma]

Can you add the example of the non-full rank lattices?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.94%. Comparing base (bd5a960) to head (cde5b4a).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1665      +/-   ##
==========================================
- Coverage   76.04%   75.94%   -0.10%     
==========================================
  Files         361      361              
  Lines      113532   113785     +253     
==========================================
+ Hits        86336    86417      +81     
- Misses      27196    27368     +172     

Files with missing lines	Coverage Δ
src/QuadForm/Quad/GenusRep.jl	86.65% <100.00%> (ø)

... and 51 files with indirect coverage changes