docs(bigquery): add connection explainer to bigquery backend docs

docs/backends/BigQuery.md

@@ -1,8 +1,80 @@
 ---
 backend_name: Google BigQuery
 backend_url: https://cloud.google.com/bigquery
-backend_module: bigquery
-backend_param_style: connection parameters
 ---
 
-{% include 'backends/template.md' %}
+## Install
+
+Install `ibis` and dependencies for the BigQuery backend:
+
+=== "pip"
+
+    ```sh
+    pip install 'ibis-framework[bigquery]`
+    ```
+
+{% for mgr in ["conda", "mamba"] %}
+=== "{{ mgr }}"
+
+    ```sh
+    {{ mgr }} install -c conda-forge ibis-bigquery
+    ```
+
+{% endfor %}
+
+## Usage
+
+### `ibis.bigquery.connect`
+
+```python
+con = ibis.bigquery.connect(
+    project_id="ibis-bq-project",
+    dataset_id="testing",
+)
+```
+
+<!-- prettier-ignore-start -->
+!!! info "`ibis.bigquery.connect` is a thin wrapper around [`ibis.backends.bigquery.Backend.do_connect`][ibis.backends.bigquery.Backend.do_connect]."
+<!-- prettier-ignore-end -->
+
+### Connection Parameters
+
+<!-- prettier-ignore-start -->
+::: ibis.backends.bigquery.Backend.do_connect
+    options:
+      heading_level: 4
+<!-- prettier-ignore-end -->
+
+### `ibis.connect` URL format
+
+In addition to `ibis.bigquery.connect`, you can also connect to BigQuery by
+passing a properly formatted BigQuery connection URL to `ibis.connect`
+
+```python
+con = ibis.connect(f"bigquery://{project_id}/{dataset_id}")
+```
+
+<!-- prettier-ignore-start -->
+!!! info "This assumes you have already authenticated via the `gcloud` CLI"
+<!-- prettier-ignore-end -->
+
+### Finding your `project_id` and `dataset_id`
+
+Log in to the [Google Cloud Console](https://console.cloud.google.com/bigquery)
+to see which `project_id`s and `dataset_id`s are available to use.
+
+![bigquery_ids](./images/bigquery_connect.png)
+
+### BigQuery Authentication
+
+The simplest way to authenticate with the BigQuery backend is to use [Google's `gcloud` CLI tool](https://cloud.google.com/sdk/docs/install-sdk).
+
+Once you have `gcloud` installed, you can authenticate to BigQuery (and other Google Cloud services) by running
+
+```sh
+gcloud auth login
+```
+
+For any authentication problems, or information on other ways of authenticating,
+see the [`gcloud` CLI authorization
+guide](https://cloud.google.com/sdk/docs/authorizing).