docs(fix): revert prettier formatting on markdown files (#1612)

Prettier formatting our markdown files is causing bugs because of the
differences between Gatsby's parser and Prettier's. Also, Prettier
formats the inline code-blocks containing example CMS configs, but the
formatting it uses doesn't really make much sense or match the suggested
CMS config style.

It doesn't actually make much sense to format the docs anyway, since we
use the CMS itself to edit/generate them.

website/content/docs/widgets/index.md

@@ -10,19 +10,19 @@ Widgets are specified as collection fields in the Netlify CMS `config.yml` file.
 
 To see working examples of all of the built-in widgets, try making a 'Kitchen Sink' collection item on the [CMS demo site](https://cms-demo.netlify.com). (No login required: click the login button and the CMS will open.) You can refer to the demo [configuration code](https://github.com/netlify/netlify-cms/blob/master/packages/netlify-cms/example/config.yml) to see how each field was configured.
 
+
 ## Common widget options
 
 The following options are available on all fields:
 
 - `required`: specify as `false` to make a field optional; defaults to `true`
 - `pattern`: add field validation by specifying a list with a [regex pattern](https://regexr.com/) and an error message; more extensive validation can be achieved with [custom widgets](https://www.netlifycms.org/docs/custom-widgets/#advanced-field-validation)
-
   - **Example:**
         ```yaml
-        - label: 'Title'
-          name: 'title'
-          widget: 'string'
-          pattern: ['.{12,}', 'Must have at least 12 characters']
+        - label: "Title"
+          name: "title"
+          widget: "string"
+          pattern: [".{12,}", "Must have at least 12 characters"]
         ```
 
 ## Default widgets