Cleaning up some comments

[markuswntr]

This PR contains a few minor changes to comments, namely:

• Combinations.swift contained an invalid source code example
• Rotate.swift was missing the definition of n (for (O(n))
• Trim.swifts formatting diverged from the rest of the project
  • Comments did not break on or before line # 80
  • Replaced the delimiter names parameters and complexity with Parameters and Complexity respectively
  • Replaced `O(n)` and `n` with O(*n*) and *n* respectively

Checklist

• I've added at least one test that validates that my change is working, if appropriate
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary

[natecook1000]

Thanks for taking care of these, @markuswntr! 👏