gh-36388: fix typographic typos
Fix a few typographic typos in `thematic_tutorials/tutorial-
implementing-algebraic-structures`: missing double backtick, missing
underscore.
- [X] The title is concise, informative, and self-explanatory.
- [X] The description explains in detail what this PR is about.
URL: https://github.com/sagemath/sage/pull/36388
Reported by: Martin Rubey
Reviewer(s): David Coudert, Martin Rubey
