gh-37506: Improving the documentation of Discrete Dynamical Systems by fixing typos and eliminating repeated sentences
The typos and the repeated sentences issue in the documentation of
[Discrete dynamical systems](https://doc.sagemath.org/html/en/reference/
dynamics/sage/dynamics/finite_dynamical_system.html) is solved
Fixes #37188
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URL: https://github.com/sagemath/sage/pull/37506
Reported by: Dhrumil Raigagla
Reviewer(s): Matthias Köppe
