diff --git a/website/site/content/docs/collection-types.md b/website/site/content/docs/collection-types.md
index d634e7f6..a81a01aa 100644
--- a/website/site/content/docs/collection-types.md
+++ b/website/site/content/docs/collection-types.md
@@ -2,14 +2,12 @@
 title: Collection Types
 position: 27
 ---
-
 # Collection Types
 
 All editable content types are defined in the `collections` field of your `config.yml` file, and display in the left sidebar of the Content page of the editor UI.
 
 Collections come in two main types: `folder` and `files`.
 
-
 ## Folder collections
 
 Folder collections represent one or more files with the same format, fields, and configuration options, all stored within the same folder in the repository. You might use a folder collection for blog posts, product pages, author data files, etc.
@@ -38,12 +36,12 @@ The entries for any folder collection can be filtered based on the value of a si
 
 The `filter` option requires two fields:
 
-- `field`: the name of the collection field to filter on
-- `value`: the desired field value
+* `field`: the name of the collection field to filter on
+* `value`: the desired field value
 
 The example below creates two collections in the same folder, filtered by the `language` field. The first collection includes posts with `language: en`, and the second, with `language: es`.
 
-``` yaml
+```yaml
 collections:
   - label: "Blog in English"
     name: "english_posts"
@@ -63,16 +61,17 @@ collections:
       - {label: "Contenido", name: "body", widget: "markdown"}      
 ```
 
-
 ## File collections
 
 A `files` collection contains one or more uniquely configured files. Unlike items in `folder` collections, which repeat the same configuration over all files in the folder, each item in a `files` collection has an explicitly set path, filename, and configuration. This can be useful for unique files with a custom set of fields, like a settings file or a custom landing page with a unique content structure.
 
 When configuring a `files` collection, each file in the collection is configured separately, and listed under the `files` field of the collection. Each file has its own list of `fields`, and a unique filepath specified in the `file` field (relative to the base of the repo).
 
+**Note:** Files listed in a file collection must already exist in the repo, and must have a valid value for the file type. For example, an empty file works as valid YAML, but a JSON file must have a non-empty value to be valid, such as an empty object.
+
 Example:
 
-``` yaml
+```yaml
 - label: "Pages"
   name: "pages"
   files: