Fix documentation of findall behaviour

[adomasbaliuka]

The current documentation claims that findall(!iszero, my_sparse_matrixcsc) would be "including stored entries equal to zero".

This seems counter-intuitive to me. It also seems to be wrong (unless I'm missing something):

julia> M = sparse([1, 2], [1,1], [0, 1], 2, 2)
2×2 SparseMatrixCSC{Int64, Int64} with 2 stored entries:
 0  ⋅
 1  ⋅

julia> findnz(M)
([1, 2], [1, 1], [0, 1])

julia> findall(!iszero, M)
1-element Vector{CartesianIndex{2}}:
 CartesianIndex(2, 1)

I propose to correct the documentation.

[codecov]

Codecov Report

Merging #452 (17cddd6) into main (05ac950) will not change coverage.
The diff coverage is n/a.

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[ViralBShah]

That's a nice catch. Thank you!