Add docs interlinks

[sethaxen]

This PR adds docs interlinks using DocumenterInterLinks, linking out to relevant Statistics/StatsBase methods and to sections of the MLJ docs.

[coveralls]

Pull Request Test Coverage Report for Build 12129334127

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 96.705%

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Totals
Change from base Build 12109032772:	0.0%
Covered Lines:	851
Relevant Lines:	880

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💛 - Coveralls

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.70%. Comparing base (9d3e4ca) to head (3635c6d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #131   +/-   ##
=======================================
  Coverage   96.70%   96.70%           
=======================================
  Files          10       10           
  Lines         880      880           
=======================================
  Hits          851      851           
  Misses         29       29           

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[sethaxen]

The main downside I see to this approach is that links in the REPL are somewhat less pretty/informative. e.g.

julia> """
           my_mean(x)
           
       My version of [`Statistics.mean`](@extref). See [Statistics docs](@extref Statistics `Statistics`).

       See also: [`my_std`](@ref).
       """
       function my_mean end
my_mean

help?> my_mean
search: my_mean

  my_mean(x)

  My version of Statistics.mean (@extref). See Statistics docs (@extref Statistics `Statistics`).

  See also: my_std.

Still, I think this is better than the alternative of not linking out to other docs.