[Config] tweaked dumper to indent multi-line info

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | - 

Little cosmetic tweak.

before:
```yaml
    # router configuration
    router:               
        resource:             ~ # Required
        type:                 ~ 
        http_port:            80 
        https_port:           443 

        # set to true to throw an exception when a parameter does not match the requirements
set to false to disable exceptions when a parameter does not match the requirements (and return null instead)
set to null to disable parameter checks against requirements
'true' is the preferred configuration in development mode, while 'false' or 'null' might be preferred in production
        strict_requirements:  true 

    # session configuration
    session:              
```
after:
```yaml
    # router configuration
    router:               
        resource:             ~ # Required
        type:                 ~ 
        http_port:            80 
        https_port:           443 

        # set to true to throw an exception when a parameter does not match the requirements
        # set to false to disable exceptions when a parameter does not match the requirements (and return null instead)
        # set to null to disable parameter checks against requirements
        # 'true' is the preferred configuration in development mode, while 'false' or 'null' might be preferred in production
        strict_requirements:  true 

    # session configuration
```