Documentation unclear about where to run Stackctl

[pbrisbin]

The documentation for --dir says:

Where to find specifications. Default is ..

The documentation about specifications says,

Specification files ("specs") have the following path structure:

stacks/{account-id}.{account-name}/{region}/{stack-name}.yaml

Users have indicated that does not clearly convey that Stackctl expects to be run in, or use a --dir that is, a directory containing ./stacks and ./templates.

. <-- HERE
├── stacks/
│   └── {account-id}.{account-name}/
│       └── {region}/
│           └── {stack-name}.yaml
│
└── templates/
    └── {template}.yaml

Thus, they can make a few incorrect guesses:

1. Be in the directory with ./{stack-name}.yaml, assuming the file is the specification and going by --dir documentation
2. Be in the stacks sub-directory
3. Be in the correct directory, but have the wrong AWS account active

We should rewrite these things to clarify that, and probably add an EXAMPLES section that makes it more concrete, and thus clearer.