Why this change?
When editing a objects typed theme setting, the input fields which are
rendered should include a description so that the user knows the purpose
of the field which they are changing.
What does this change do?
This change adds support for adding description to each property in the
schema for an object by following a given convention in the locale file.
For a schema like this:
```
objects_setting:
type: objects
schema:
name: section
properties:
name:
type: string
required: true
links:
type: objects
schema:
name: link
properties:
name:
type: string
required: true
validations:
max_length: 20
url:
type: string
```
Description for each property in the object can be added like so:
```
en:
theme_metadata:
settings:
objects_setting:
description: <description> for the setting
schema:
properties:
name: <description for the name property>
links:
name: <description for the name property in link>
url: <description for the url property in link>
```
If the a description is not present, the input field will simply not
have an description.
Also note that a description for a theme setting can now be added like
so:
```
en:
theme_metadata:
settings:
some_other_setting: <This will be used as the description>
objects_setting:
description: <This will also be used as the description>
```
