docs(firestore-bigquery-export): update CLI params description

firestore-bigquery-export/guides/GENERATE_SCHEMA_VIEWS.md

@@ -94,6 +94,8 @@ installation of the extension:
 
 - `${param:PROJECT_ID}`: the project ID for the Firebase project in
   which you installed the extension
+- `${param:BIGQUERY_PROJECT_ID}`: the project ID for the GCP project that contains
+  the BigQuery instance.
 - `${param:DATASET_ID}`: the ID that you specified for your dataset during
   extension installation
 - `${param:TABLE_ID}`: the common prefix of BigQuery views to generate
@@ -116,6 +118,7 @@ via `npm` (the Node Package Manager).
     $ npx @firebaseextensions/fs-bq-schema-views \
       --non-interactive \
       --project=${param:PROJECT_ID} \
+      --big-query-project=${param:BIGQUERY_PROJECT_ID} \
       --dataset=${param:DATASET_ID} \
       --table-name-prefix=${param:TABLE_ID} \
       --schema-files=./test_schema.json

firestore-bigquery-export/guides/IMPORT_EXISTING_DOCUMENTS.md

@@ -32,6 +32,7 @@ Warning: A `collectionGroup` query will target every collection in your Firestor
 The import script requires several values from your installation of the extension:
 
 - `${PROJECT_ID}`: the project ID for the Firebase project in which you installed the extension
+- `${BIGQUERY_PROJECT_ID}`: the project ID for the GCP project in which the BigQuery instance is located. Defaults to Firebase project ID.
 - `${COLLECTION_PATH}`: the collection path that you specified during extension installation
 - `${COLLECTION_GROUP_QUERY}`: uses a `collectionGroup` query if this value is `"true"`. For any other value, a `collection` query is used.
 - `${DATASET_ID}`: the ID that you specified for your dataset during extension installation
@@ -61,6 +62,8 @@ Run the import script using [`npx` (the Node Package Runner)](https://www.npmjs.
 
     **Note**: The script can be run non-interactively. To see its usage, run the above command with `--help`.
 
+1.  _(Optional)_ When prompted, you can enter the BigQuery project ID to use a BigQuery instance located in a GCP project other than your Firebase project.
+
 1.  When prompted, enter the Cloud Firestore collection path that you specified during extension installation, `${COLLECTION_PATH}`.
 
 1.  _(Optional)_ You can pause and resume the import at any time: