help text for juju list-credentials needs improving

[Peter Matulis]

e.g.:

Usage: juju list-credentials [options] [<cloud name>]

Summary:
Lists credentials for a cloud.

Options:

--format (= tabular)
    Specify output format (json|tabular|yaml)
-o, --output (= "")
    Specify output file
--show-secrets (= false)
    Show secrets

Details:
Credentials are used with `juju bootstrap` and `juju create-model`.
An arbitrary "credential name" is used to represent credentials, which are added either via `juju add-credential` or `juju autoload-credentials`. Note that there can be multiple sets of credentials and thus multiple names.
Actual authentication material is exposed with the '--show-secrets' option.
A controller and subsequently created models can be created with a different set of credentials but any action taken within the model (e.g.: `juju deploy`; `juju add-unit`) applies the set used to create the model. Recall that when a controller is created a 'default' model is also created.
Credentials denoted with an asterisk '*' are currently set as the default for the given cloud.

Examples:

    juju list-credentials
    juju list-credentials aws
    juju list-credentials --format yaml --show-secrets

See also: add-credential
          remove-credential
          set-default-credential
          autoload-credentials

[Reed O'Brien (reedobrien)]

Usage: juju list-credentials [options] [<cloud name>]

Summary:
Lists credentials for a cloud.

Options:
--format (= tabular)
    Specify output format (json|tabular|yaml)
-o, --output (= "")
    Specify an output file
--show-secrets (= false)
    Show secrets

Details:
Credentials are used with `juju bootstrap` and `juju create-model`.
An arbitrary "credential name" is used to represent credentials, which are
added either via `juju add-credential` or `juju autoload-credentials`.
Note that there can be multiple sets of credentials and thus multiple
names.
Actual authentication material is exposed with the '--show-secrets'
option.
A controller and subsequently created models can be created with a
different set of credentials but any action taken within the model (e.g.:
`juju deploy`; `juju add-unit`) applies the set used to create the model.
Recall that when a controller is created a 'default' model is also
created.
Credentials denoted with an asterisk '*' are currently set as the default
for the given cloud.

Examples:
    juju list-credentials
    juju list-credentials aws
    juju list-credentials --format yaml --show-secrets

See also:
    add-credential
    remove-credential
    set-default-credential
    autoload-credentials