Add documentation for workbook (Azure-Samples#639)

* Add documentation for workbook

Required by Azure-Samples#418

* Remove space

Co-authored-by: Ross Smith <ross-p-smith@users.noreply.github.com>

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Co-authored-by: Ross Smith <ross-p-smith@users.noreply.github.com>

docs/workbook.md

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+# Workbook
+
+This project leverages [Azure Workbooks](https://learn.microsoft.com/en-us/azure/azure-monitor/visualize/workbooks-overview)
+to aggregate monitoring data from various Azure resources.
+
+The workbook's exported JSON is located in the [../infra/workbooks/workbook.json](../infra/workbooks/workbook.json)
+file. The actual resource names have been replaced with placeholders, which get populated during the workbook's deployment.
+
+## Modifying the Workbook
+
+The most straightforward method to modify the workbook is through the UI, followed by re-exporting the JSON file.
+
+To do this, navigate to the workbook resource and:
+
+1. Click on 'Edit'
+   ![Edit Workbook](images/workbook-edit.png)
+2. Click on 'Advanced Editor'
+   ![Advanced Editor](images/workbook-advanced-editor.png)
+3. Copy or download the contents into the [../infra/workbooks/workbook.json](../infra/workbooks/workbook.json) file
+   ![Workbook JSON](images/workbook-json.png)
+4. Replace the actual resource names with the corresponding placeholders:
+   - `/subscriptions/00000000-0000-0000-0000-00000000000` -> `{subscription-id}`
+   - `rg-<your-resource-group-name>` -> `{resource-group}`
+   - `hosting-plan-<your-resource-token>` -> `{app-service-plan}`
+   - `backend-<your-resource-token>` -> `{backend-app-service}`
+   - `web-<your-resource-token>` -> `{web-app-service}`
+   - `web-<your-resource-token>-admin` -> `{admin-app-service}`
+   - `doc-processing` -> `{event-grid}`
+   - `la-<your-resource-token>` -> `{log-analytics}`
+   - `openai-<your-resource-token>` -> `{open-ai}`
+   - `search-<your-resource-token>` -> `{ai-search}`
+   - `str<your-resource-token>` -> `{storage-account}`
+
+## Adding New Resources to the Workbook
+
+To simplify the process of replacing resource names with placeholders, we've added hidden parameters that reference the
+resources. These parameters are visible when you're editing the workbook:
+
+![Resource Parameters](images/workbook-resource-parameters.png)
+
+If you need to add a new resource to the workbook, please add this as a hidden parameter, then reference that parameter
+in your metric or query. The easiest way to do this is to duplicate an existing parameter and change it to the resource
+type you require.
+
+## Recommended Graph Settings
+
+To enhance the workbook's usability, we recommend the following settings, which can be found under `Advanced Settings`:
+- `Show open in Metrics Explorer button when not editing`: This allows users to easily modify or edit the query if
+required for a specific reason.
+- `Enable time range brushing` + `Export selected time range as parameter: timerange`: This allows users to easily
+modify the time range and zoom in on data by simply highlighting the time range on the graph.
+
+## Tabs
+
+To implement tab functionality, we first need to organize our graphs into groups. Then, in `Advanced Settings` for the
+groups, we enable the setting `Make this item conditionally visible`, adding a condition of `selTab equals <tab-name>`.
+
+We then add a new links section to the workbook, of type tabs. Where the action of each tab is `Set a parameter value`
+where the value is `selTab` and the settings is the name of the tab.
+
+![Workbook Tabs](images/workbook-tabs.png)