Mutual Information I(𝒶, 𝒷) and improving doctests/documentation in entanglement.jl

[Fe-r-oz]

This PR aims to introduce Mutual Information I(A,B) along with improving the doctests and documentation in the entanglement.jl .

In the future, if you like, it would be better to have a entanglement introduced in the manual of either "algebra" or upcoming "circuit simulation" manual.

In the papers, there were many graphs, I think based on entanglement entropy that could be reproduced in a tutorial fashion. Hopefully, this sounds interesting.
....
If you want to submit an unfinished piece of work in order to get comments and discuss, please mark the pull request as a draft and ping the repository maintainer.

Please address only one topic or issue per pull request! Many small PRs are much easier to review and merge than one large PR.

Before merging, all changes and new functionality should be marked in the CHANGELOG file, but feel free to just leave your CHANGELOG notes in the PR description, to avoid merge conflicts with other requests modifying that file. The maintainer will add these CHANGELOG notes for you if you do so.

Before considering your pull request ready for review and merging make sure that all of the following are completed (please keep the clecklist as part of your PR):

• The code is properly formatted and commented.
• Substantial new functionality is documented within the docs.
• All new functionality is tested.
• All of the automated tests on github pass.

If possible, keep your git history not too wild (rebase and squash commits, keep commits small and semantically separated) so that review is easier.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.55%. Comparing base (e51a142) to head (b616cdd).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #338      +/-   ##
==========================================
+ Coverage   82.48%   82.55%   +0.06%     
==========================================
  Files          62       62              
  Lines        4186     4202      +16     
==========================================
+ Hits         3453     3469      +16     
  Misses        733      733              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[Krastanov]

thanks, this is an interesting addition. I left a few comments in.

[Fe-r-oz]

Thanks for your comments, I will polish it as per your comments.

[Fe-r-oz]

All of your suggestions have been incorporated. Thanks for your helpful suggestions.