missing samples/README.md

I just noticed that there is no docs for the actions we installed by default for the samples package
README should be located here https://github.com/openwhisk/openwhisk-catalog/tree/master/packages/samples/README.md

Readme should have at least the 4 following actions `helloWorld`, `wordCount`, and `curl`
```
$ wsk package get /whisk.system/samples --summary
package /whisk.system/samples: A suite of simple actions to help you get started with OpenWhisk
action /whisk.system/samples/helloWorld: Demonstrates logging facilities
(parameters: payload)
action /whisk.system/samples/greeting: Returns a friendly greeting
(parameters: name, place)
action /whisk.system/samples/wordCount: Count words in a string
(parameters: payload)
action /whisk.system/samples/curl: Curl a host url
(parameters: payload)
```