sage

cf589643 - gh-37630: Enhance documentation of Drinfeld module Potemine j-invariants

gh-37630: Enhance documentation of Drinfeld module Potemine j-invariants <!-- ^ Please provide a concise and informative title. --> <!-- ^ Don't put issue numbers in the title, do this in the PR description below. --> <!-- ^ For example, instead of "Fixes #12345" use "Introduce new method to calculate 1 + 2". --> <!-- v Describe your changes below in detail. --> <!-- v Why is this change required? What problem does it solve? --> <!-- v If this PR resolves an open issue, please link to it here. For example, "Fixes #12345". --> The definition of $j$-invariants, *basic* $j$-invariants and $j_k$-invariants defer in [Potemine's article](https://link.springer.com/article/10.1023/A:1009724323513) and [Papikian's book](https://link.springer.com/book/10.1007/978-3-031-19707-9). Thanks to @DavidAyotte, we follow Potemine's convention. Seeing however the growing popularity of Papikian's book, I reckon it is a good idea to add a note in the documentation addressing those differences. Also, I fixed a typo. ### Potemine:   ### Papikian:   ### :memo: Checklist <!-- Put an `x` in all the boxes that apply. --> - [x] The title is concise and informative. - [x] The description explains in detail what this PR is about. - [x] I have linked a relevant issue or discussion. - [x] I have created tests covering the changes. - [x] I have updated the documentation accordingly. ### :hourglass: Dependencies <!-- List all open PRs that this PR logically depends on. For example, --> <!-- - #12345: short description why this is a dependency --> <!-- - #34567: ... --> URL: https://github.com/sagemath/sage/pull/37630 Reported by: Antoine Leudière Reviewer(s): David Ayotte