docs: add examples for bool tensor operations

[qburke]

Summary

Added documentation examples for four boolean tensor operations in burn-tensor:

• bool_not - Boolean inversion
• bool_and - Logical AND operation
• bool_or - Logical OR operation
• bool_xor - Logical XOR operation

Changes

Added doc examples with:

• Clear descriptions of what each operation does
• Arguments and Returns sections
• Code examples
• Expected output in comments

Contributes to #2450

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.03%. Comparing base (91dd62c) to head (7633b4f).
⚠️ Report is 6 commits behind head on main.

❌ Your project check has failed because the head coverage (69.03%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4248      +/-   ##
==========================================
+ Coverage   68.96%   69.03%   +0.07%     
==========================================
  Files        1346     1409      +63     
  Lines      165578   165880     +302     
==========================================
+ Hits       114192   114520     +328     
+ Misses      51386    51360      -26     

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[laggui]

Thanks for contributing documentation 🙏

Minor comment on formatting, otherwise LGTM

[laggui]

Just to make the examples a bit more compact, we can fix the formatting following cargo fmt

fn example<B: Backend>() {
    let device = Default::default();
    let a = Tensor::<B, 2, Bool>::from_bool([[true, true], [false, false]].into(), &device);
    let b = Tensor::<B, 2, Bool>::from_bool([[true, false], [true, false]].into(), &device);
    let result = a.bool_and(b);
    println!("{result}"); // [[true, false], [false, false]]
}

for all examples