fix minor grammar issue

Fix grammar

Co-authored-by: Nate Prewitt <nate.prewitt@gmail.com>

fix minor grammar issue#

README.rst

@@ -81,7 +81,7 @@ Then, set up a default region (in e.g. ``~/.aws/config``):
    [default]
    region=us-east-1
 
-Other credentials configuration method can be found `here <https://boto3.amazonaws.com/v1/documentation/api/latest/guide/credentials.html>`__
+Other credential configuration methods can be found `here <https://boto3.amazonaws.com/v1/documentation/api/latest/guide/credentials.html>`__
 
 Then, from a Python interpreter: