fix name of secret for Algolia API key [no ci]

.github/workflows/rebuild-search-index.yml

@@ -22,5 +22,5 @@ jobs:
       uses: darrenjennings/algolia-docsearch-action@master
       with:
         algolia_application_id: ${{ secrets.ALGOLIA_APPLICATION_ID }}
-        algolia_api_key: ${{ secrets.ALGOLIA_API_KEY }}
+        algolia_api_key: ${{ secrets.ALGOLIA_WRITE_KEY }}
         file: ${{ env.CONFIG_FILE }}