[skip ci] Merge pull request #505 from nazieb/lambda-options-doc
[skip ci] Merge pull request #505 from nazieb/lambda-options-doc

Add doc for missing AWS Lambda options
testfairy/dpl,travis-ci/dpl,pengsrc/dpl,testfairy/dpl,computology/dpl,travis-ci/dpl,travis-ci/dpl,testfairy/dpl