Fix Backend docs search items (#101214)
Fixes #100944
## New
<img width="1142" alt="image" src="https://github.com/pytorch/pytorch/assets/13214530/79102f2e-8a8f-4169-be53-9248397e653c">
<img width="765" alt="image" src="https://github.com/pytorch/pytorch/assets/13214530/4e5f17e7-a445-4822-ac8a-0d73c9ed71ee">
## Old
<img width="1341" alt="image" src="https://github.com/pytorch/pytorch/assets/13214530/985b4ec9-6d11-4962-8619-3c14ec09c3d9">
<img width="1112" alt="image" src="https://github.com/pytorch/pytorch/assets/13214530/e8dcf1a9-73e7-4fd6-8adc-eb036b1bb87b">
Pull Request resolved: https://github.com/pytorch/pytorch/pull/101214
Approved by: https://github.com/albanD
