Fix typo in .env_sample file for the AWS secret access key variable
Fix typo in .env_sample file for the AWS secret access key variable

References Coursemology/coursemology.org#287

allenwq/coursemology.org,dariusf/coursemology.org,Coursemology/coursemology.org,allenwq/coursemology.org,Coursemology/coursemology.org,Coursemology/coursemology.org,allenwq/coursemology.org,nnamon/coursemology.org,Coursemology/coursemology.org,nnamon/coursemology.org,allenwq/coursemology.org,dariusf/coursemology.org,allenwq/coursemology.org,nnamon/coursemology.org,nnamon/coursemology.org,dariusf/coursemology.org,dariusf/coursemology.org,dariusf/coursemology.org,Coursemology/coursemology.org,nnamon/coursemology.org