Update docs

Author: Mariko Wakabayashi

docs/source/developers/contents.rst

@@ -285,6 +285,6 @@ An asynchronous version of the Contents API is available to run slow IO processe
 
    In most cases, the non-asynchronous Contents API is performant for local filesystems.
    However, if the Jupyter Notebook web application is interacting with a high-latent virtual filesystem, you may see performance gains by using the asynchronous version.
-   For example, if you're experiencing terminal lag in the web application due to the slow and blocking file operations, the asynchronous version may be a good option.
+   For example, if you're experiencing terminal lag in the web application due to the slow and blocking file operations, the asynchronous version can reduce the lag.
    Before opting in, comparing both non-async and async options' performances is recommended.