message: Add login examples for all options
diff: @@ -65,7 +65,7 @@ Examples:
  user).
  ```
  -#### `io init` Example
  +#### `io init` Examples
  ```text
  $ io init
  @@ -91,7 +91,7 @@ deploy_tasks:
  ```text
  $ io login --help
  -io login - Authenticate with the amazee.io API via given SSH key
  +io login - Authenticate with amazee.io via an SSH key
  Options:
  --help Show help [boolean]
  @@ -100,13 +100,40 @@ Options:
  Done in 1.86s.
  ```
  -#### `io login` Example
  +#### `io login` Examples
  +
  +By default, the login command uses the SSH private key at `$HOME/.ssh/id_rsa`.
  +
  +```text
  +$ io login
  +Login successful
  +Done in 1.28s.
  +```
  +
  +If that file does not exist, the user will be prompted for the path:
  +
  +```text
  +$ io login
  +? Path to private key file /path/to/id_rsa
  +Login successful
  +Done in 3.42s.
  +```
  +
  +The path to the key can be also passed in via the `--identity` option (short form `-i`):
  +
  +```text
  +$ io login -i /path/to/id_rsa
  +Login successful
  +Done in 1.70s.
  +```
  +
  +If the private key has a password, the user will be prompted to enter it. The password will never be saved.
  ```text
  -$ io login -i ~/.ssh/id_rsa
  +$ io login -i /path/to/id_rsa
  ? Private key password (never saved) [hidden]
  Login successful
  -Done in 2.30s.
  +Done in 4.15s.
  ```
  ### `io sites`
  @@ -117,7 +144,7 @@ io list sites
  io list sites -s my_sitegroup
  ```
  -#### `io sites` Example
  +#### `io sites` Examples
  ## Development
  