Feature/unordered node map docs

[joaquintides]

This is complete except the benchmarks, which I'll extend to cover unordered_node_map in the following days.

[cppalliance-bot]

An automated preview of the documentation is available at https://182.unordered.prtest.cppalliance.org/libs/unordered/doc/html/unordered.html

[codecov[bot]]

Codecov Report

Merging #182 (d51cee3) into develop (0597463) will not change coverage. The diff coverage is n/a.

:exclamation: Current head d51cee3 differs from pull request most recent head c189d8d. Consider uploading reports for the commit c189d8d to get more accurate results

Additional details and impacted files

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[cppalliance-bot]

An automated preview of the documentation is available at https://182.unordered.prtest.cppalliance.org/libs/unordered/doc/html/unordered.html

[cppalliance-bot]

An automated preview of the documentation is available at https://182.unordered.prtest.cppalliance.org/libs/unordered/doc/html/unordered.html

[cppalliance-bot]

An automated preview of the documentation is available at https://182.unordered.prtest.cppalliance.org/libs/unordered/doc/html/unordered.html