/func - Section 8.2: Calling Functions (2023-10-02): Rename env into envs

[sback]

In this section, it is introduced the concept of using multiple environments, rather than just one. To reflect this, I suggest renaming the variable to envs. This emphasizes that we're dealing with multiple environments.

When I taught this content, I noticed that students grasped the concept better when I mentioned that the variable could be called envs, indicating a set of environments.