Few docs cleanup

[sathvikbhagavan]

Noticed doc build was failing on master - https://github.com/SciML/GlobalSensitivity.jl/actions/runs/7455890323/job/20285675728 because of link check.

I am not sure of the reason but curl of [sciencedirect.com](http://sciencedirect.com/) results in 403 error now

> curl -I <https://www.sciencedirect.com/>
HTTP/2 403
date: Tue, 09 Jan 2024 11:03:58 GMT
...

I have added a linkcheck_ignore for articles from sciencedirect referenced.

Also noticed a few examples were not run in the doc build - so changed it to running them.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3ae0794) 92.85% compared to head (5a5a967) 92.85%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #147   +/-   ##
=======================================
  Coverage   92.85%   92.85%           
=======================================
  Files          11       11           
  Lines         840      840           
=======================================
  Hits          780      780           
  Misses         60       60           

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[Vaibhavdixit02]

Thanks!