docs: more info to README

includes/bylines/README.md

@@ -1,10 +1,14 @@
 # Custom Bylines
 
+**This feature is under development and is not meant to be used in production sites**
+
 This feature allows authors to add custom bylines to posts.
 
 ## How it works
 
-When you enable this feature, a new settings panel will be added to the post editor sidebar. You can use this panel to add a custom byline. The byline will be displayed before the post content.
+When you enable this feature, a new settings panel will be added to the post editor sidebar. You can use this panel to add a custom byline. The byline will be displayed before the post content. (See Data section below for the format of bylines)
+
+Once inserted, the custom byline will be inserted at the top of the content, both in the Editor and in the front-end site (temporary behavior for migration QA purposes)
 
 ## Usage
 
@@ -21,4 +25,4 @@ Bylines are stored as post meta and consists of the following fields:
 | Name                          | Type      | Stored As   | Description                                                                                                           |
 | ----------------------------- | --------- | ----------- | --------------------------------------------------------------------------------------------------------------------- |
 | `_newspack_byline_active`     | `boolean` | `post_meta` | Whether custom byline is active for the post                                                                          |
-| `_newspack_byline`            | `string`  | `post_meta` | The custom byline. Author links can be included by wrapping text in the Author tag (`<Author id=5>Jane Doe</Author>`) |
+| `_newspack_byline`            | `string`  | `post_meta` | The custom byline. Author links can be included by wrapping text in the Author tag (`by <Author id=5>Jane Doe</Author> and Eric Doe`) |