URL fragments show up as tags

I have a URL fragment in my vault containing:

```markdown
thanks to [Vite's HMR feature](https://vitejs.dev/guide/features.html#hot-module-replacement).
```

This shows up as a tag `hot-` in my code:

```python
vault = otools.Vault(vault_path).connect().gather()
tags_index = vault.tags_index
```