Docs improvement, sparsity and symbolic AD

[mohamed82008]

No description provided.

[codecov-commenter]

Codecov Report

Merging #141 (a224e0b) into master (f03f541) will decrease coverage by 0.34%.
The diff coverage is 89.65%.

❗ Current head a224e0b differs from pull request most recent head 2d04235. Consider uploading reports for the commit 2d04235 to get more accurate results

@@            Coverage Diff             @@
##           master     #141      +/-   ##
==========================================
- Coverage   90.00%   89.65%   -0.35%     
==========================================
  Files           2        1       -1     
  Lines          30       29       -1     
==========================================
- Hits           27       26       -1     
  Misses          3        3              

Impacted Files	Coverage Δ
src/Nonconvex.jl	89.65% <89.65%> (-10.35%)	⬇️

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