Add bottom-up non-recursive merge sort

[thealgorithms]

Add bottom-up non-recursive merge sort

[cclauss]

Sounds awesome! No need to open an issue... You can just directly create a pull request.

Should we use Doxygen more broadly across the repo? Maybe make a GitHub Action that autogenerates docs on pull requests?

[Albirair]

That's great, I will a pull request.
Regarding Doxygen, it would be amazing to use it across the repo either for generation of documentation or facilitating programming since IDE can recognize it and display its information as needed. Although, I don't feel excited about making such documentation be generated on GitHub, due to increasing repo size and the fact it can be generated locally.

[cclauss]

Let's try to automate Doxygen for just one algorithm to see how it works and determine its efficacy.