Documentation Page needed for Bulk Search

### Proposal

Currently, there is no easily accessible documentation from the Bulk Search page detailing how to properly use it. It would probably be best if it was linked to a 'help' page of some kind, to help users that might otherwise struggle with it.

### Justification

This problem addresses a lack of well-explained instructions and guidance for Bulk Search. It will primarily impact audiences that are unfamiliar with API keys, and it will explain the reason behind the 'beta' tag that will soon be placed on that extraction option.

The predicted impact will likely be minor, but useful. Success will be a new page created that has detailed descriptions for any users that are struggling to make proper use of the UI, likely with some visual examples to go with a text-based explanation.

### Breakdown

#### Requirements Checklist

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#### Related files

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#### Stakeholders

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#### Instructions for Contributors

Please [run these commands](https://github.com/internetarchive/openlibrary/wiki/Git-Cheat-Sheet#working-on-your-branch) to ensure your repository is up to date **before** [creating a new branch](https://github.com/internetarchive/openlibrary/wiki/Git-Cheat-Sheet#making-changes-and-creating-a-pull-request) to work on this issue and **each time after** pushing code to Github, because the pre-commit bot may add commits to your PRs upstream.