Simpler first README example, also ref to Roots.jl. Fixes #264.

[mauro3]

Whilst I've used a few bells and whistles of the excellent NLsolve, most of the time I just quickly want to solve a system of nl equations without any thoughts about performance. This now shows this as the top-most example in the README. Issue #264 suggests that at least one more person would appreciate a simpler first example (I also added the reference to Roots.jl).

[pkofod]

Thanks.

[codecov[bot]]

Codecov Report

Merging #271 (055b55f) into master (2196728) will increase coverage by 0.55%. The diff coverage is n/a.

:exclamation: Current head 055b55f differs from pull request most recent head 6f872f9. Consider uploading reports for the commit 6f872f9 to get more accurate results

@@            Coverage Diff             @@
##           master     #271      +/-   ##
==========================================
+ Coverage   87.57%   88.12%   +0.55%     
==========================================
  Files          12       12              
  Lines         531      556      +25     
==========================================
+ Hits          465      490      +25     
  Misses         66       66              

Impacted Files	Coverage Δ
src/NLsolve.jl	50.00% <0.00%> (-16.67%)	:arrow_down:
src/solvers/newton.jl	100.00% <0.00%> (ø)
src/nlsolve/fixedpoint.jl	100.00% <0.00%> (ø)
src/objectives/helpers.jl	100.00% <0.00%> (ø)
src/solvers/trust_region.jl	98.19% <0.00%> (+0.05%)	:arrow_up:
src/solvers/anderson.jl	95.00% <0.00%> (+0.26%)	:arrow_up:
src/nlsolve/utils.jl	97.56% <0.00%> (+0.26%)	:arrow_up:
src/solvers/broyden.jl	75.00% <0.00%> (+0.27%)	:arrow_up:
src/nlsolve/nlsolve.jl	93.10% <0.00%> (+1.10%)	:arrow_up:
src/solvers/mcp_func_defs.jl	75.00% <0.00%> (+2.77%)	:arrow_up:
... and 1 more

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[ChrisRackauckas]

Reference to NonlinearSolve.jl as a non-allocating version of Roots.jl?

[mauro3]

Ok, I added that reference as a second commit. As stated over in #264, a full summary of what package to use when would be good, but in another PR.