Entitymut doc changes for #24596

[MoRusty]

Objective

• Describe the objective or issue this PR addresses.
• Fixes Docs for EntityWorldMut::get_components_mut_unchecked are incorrect #24596

Solution

• Describe the solution used to achieve the objective above.
• Changed get_components methods that use result instead of option to return the correct type instead of None.
• Moved safety above example for get/into_components_mut

Testing

• Did you test these changes? If so, how? Yes, ran "cargo run -p ci -- doc" and tests came back ok
• Are there any parts that need more testing? Not that I'm aware of.
• How can other people (reviewers) test your changes? Is there anything specific they need to know? Read the comments and check they are correct. there shouldn't be a fn returning type result that returns None on the fail.
• If relevant, what platforms did you test these changes on, and are there any important ones you can't test? N/A

---

[github-actions]

Welcome, new contributor!

Please make sure you've read our contributing guide, as well as our policy regarding AI usage, and we look forward to reviewing your pull request shortly ✨

[SpecificProtagonist]

The docs of QueryAccessError should also be updated.

(I've also noticed that the has_conflicts mentioned therein has unclear docs and get_componetns_mut_unchecked technically violates the safety preconditions of WorldQuery::init_fetch, but that's a separate issue).