Update and reorganize README.md

[odow]

x-ref jump-dev/JuMP.jl#3624

I've made quite a few changes, so it's probably best viewed https://github.com/odow/Optim.jl/blob/patch-1/README.md

Main changes are:

• Remove table of badges
• Use explicit Markdown links
• Remove mathematical description of rosebbrock
• Remove suggestion to tag @pfkod explicitly
• Fix JuMP example, which @blegat got wrong 😆 (missing objective sense)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ca3513f) 84.97% compared to head (c2f7cd6) 84.85%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1076      +/-   ##
==========================================
- Coverage   84.97%   84.85%   -0.12%     
==========================================
  Files          46       46              
  Lines        3480     3480              
==========================================
- Hits         2957     2953       -4     
- Misses        523      527       +4     

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[odow]

Will look like https://jump.dev/JuMP.jl/previews/PR3624/packages/Optim/

[pkofod]

Looks good. I did suggest a change, because the slack channel name has math- first

[odow]

Done.

[pkofod]

Thanks