Rewrite the description for File System Isolation

Rewrite the description for the File System Isolation section so it's grammatically correct.

1 files changed, 3 insertions, 3 deletions

diff --git a/docs/testing.rst b/docs/testing.rst
index 4d9ed67..52a888d 100644
--- a/docs/testing.rst
+++ b/docs/testing.rst
@@ -82,9 +82,9 @@ For example, if you want to run your tests against a fixed terminal width you ca
 File System Isolation
 ---------------------
 
-For basic command line tools that want to operate with the file system, the
-:meth:`CliRunner.isolated_filesystem` method comes in useful which sets up
-an empty folder and changes the current working directory to:
+For basic command line tools with file system operations, the
+:meth:`CliRunner.isolated_filesystem` method is useful for setting the
+current working directory to a new, empty folder.
 
 .. code-block:: python
    :caption: cat.py