Provide more example commands for creating external domain service

[mheadd]

The documentation on creating an external domain service should be clarified by showing more examples of how to run the command needed to create the service, using different plans and options. The current documentation has some examples, but they may be hard to find on the page and may not be helpful to users with specific usage scenarios (e.g., without CDN).

Additionally, some users report that using JSON formatted options inline with the command does not work as expected, but that an external JSON file with options does work (as documented here). We should add examples showing that approach as well.

[mheadd]

Per, @soutenniza - the CF docs on create-service have specific examples for Windows users. We should make sure to include these, or point out the differences, as our docs tend to skew toward non-Windows users in some places.