Fix two misplaced sentences in validation errors documentation

[ananiavito]

Change Summary

1. The sentence "This error is also raised for strict fields when the input value is not an instance of bool." was under the section for the "bytes_invalid_encoding" error instead of the section for the "bool_type" error. I moved it accordingly.
2. The sentence "This error is also raised for strict fields when the input value is not an instance of Decimal.", related to the "decimal_type" validation error , was present also under the section for the "decimal_whole_digits" error. I deleted it from the "decimal_whole_digits" section.

Please review.

[codspeed-hq]

CodSpeed Performance Report

Merging #11302 will not alter performance

_{Comparing ananiavito:main (b52fa48) with main (fa61ff8)}

Summary

✅ 45 untouched benchmarks

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[Viicos]

Thanks for the fix