Incorrect anchors on some TOC

On this page:

https://preview.bazel.build/reference/be/common-definitions

clicking the first TOC entry:

goes nowhere with the url

```
https://preview.bazel.build/reference/be/common-definitions#sh-tokenization
```

clicking it on the rhs navigation:

correctly links to the right url:

```
https://preview.bazel.build/reference/be/common-definitions#bourne-shell-tokenization
```

somehow on the existing docs this works https://bazel.build/reference/be/common-definitions#sh-tokenization, i guess we should probably just fix the source, but maybe we can also validate missing anchors?

Start from the preview page at reference/be/common-definitions and compare the TOC link for “sh-tokenization” with the working RHS navigation link for “bourne-shell-tokenization.” Locate the source that generates this page and determine why the anchors differ; done means the TOC link reaches the intended section, with missing-anchor validation handled only if the existing source supports it.

Written by the indexing model from the issue text.