Add some docs to svd

[andreasnoack]

No description provided.

[codecov-io]

Codecov Report

Merging #49 into master will decrease coverage by 19.92%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master      #49       +/-   ##
===========================================
- Coverage   72.77%   52.84%   -19.93%     
===========================================
  Files          10       10               
  Lines        1381     1404       +23     
===========================================
- Hits         1005      742      -263     
- Misses        376      662      +286

Impacted Files	Coverage Δ
src/svd.jl	59.67% <ø> (-16.04%)	⬇️
src/householder.jl	37.34% <0%> (-44.93%)	⬇️
src/cholesky.jl	67.64% <0%> (-32.36%)	⬇️
src/eigenGeneral.jl	50.3% <0%> (-28.58%)	⬇️
src/qr.jl	71.15% <0%> (-26.89%)	⬇️
src/tridiag.jl	53.84% <0%> (-23.08%)	⬇️
src/lapack.jl	28.04% <0%> (-22.77%)	⬇️
src/eigenSelfAdjoint.jl	72.29% <0%> (-14.09%)	⬇️
src/rectfullpacked.jl	76.38% <0%> (-9.73%)	⬇️
... and 1 more

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