Improve documentation for hive.gcs.endpoint (facebookincubator#11289)

Summary:
This commit got left out here facebookincubator#11235
I removed the default endpoint value from that PR since it was not required.

Pull Request resolved: facebookincubator#11289

Reviewed By: kagamiori

Differential Revision: D64619516

Pulled By: kgpai

fbshipit-source-id: 81f301a9a529af8502a4cfe4cfc0102b19e554c9

velox/docs/configs.rst

@@ -644,7 +644,7 @@ Each query can override the config by setting corresponding query session proper
    * - hive.gcs.endpoint
      - string
      -
-     - The GCS storage endpoint server.
+     - The GCS storage URI.
    * - hive.gcs.json-key-file-path
      - string
      -