Update wait_for_afi.md

Author: kyyalama2

hdk/docs/wait_for_afi.md

@@ -7,12 +7,15 @@ send an email with the results.
 The return code of the script will be 0 if the AFI was successfully created.
 The script should be in your path after sourcing `hdk_setup.sh`.
 
-The script uses theh AWS Simple Notification Service (SNS) to send email
+The script uses the AWS Simple Notification Service (SNS) to send email
 notifications so you must have permissions to create an SNS topic, add a
 subscription, and publish to the SNS topic.
 By default the topic name used is CREATE_AFI but the topic name can be
 changed using the `--sns-topic` option.
 
+Note: Please note that the developer kit is currently based on Python2 and wait_for_afi script requires boto3 installation compatible with Python2. An older version of boto3 compatible with Python2 can be installed, for example, using
+sudo pip install boto3==1.16
+
 Example usage:
 
 `wait_for_afi.py --afi `*`AFI-ID`*` --notify --email `*`email-address`*