Document manifest includes

[purplecabbage]

Recent additions [1] to aio-cli-app-plugin allow the use of include in Project Firefly manifest.yml
This same functionality will soon be available in aio-cli-plugin-runtime also. There is no definitive documentation for us to refer to in open-whisk, so we need to clearly document it ourselves for Firefly app developers.

 include:
  - ["actions/my-action/images/*.jpg", "jpegs/"]

[1] adobe/aio-lib-web#124

Some reference info can be found here:
https://medium.com/openwhisk/whisk-deploy-zip-actions-with-include-exclude-30ba6d96ad8b

Openwhisk include zipping code (go) is here:
https://github.com/apache/openwhisk-wskdeploy/blob/cbe7c52d99c1ead5172946d3aeb33adb5d5c40b2/utils/zip.go#L115

Here is a test file with various include permutations:
https://github.com/apache/openwhisk-wskdeploy/blob/8e4a79926039612c5242f06942c3382919acc021/tests/src/integration/zipactionwithinclude/manifest.yml

Openwhisk Issue:
apache/openwhisk-wskdeploy#1107
apache/openwhisk-wskdeploy#991

[meryllblanchet]

I'll work on this one in the Firefly docs.

[meryllblanchet]

Closing in favor of AdobeDocs/app-builder#60