Merge pull request WordPress#5547 from amdrew/issue/5546

Fix `__experimentalRegisterSidebar`/`__experimentalActivateSidebar` typo in documentation

fixes WordPress#5546

edit-post/api/README.md

@@ -11,7 +11,7 @@ This method takes two arguments:
 - a `name` to identify the sidebar. This name should contain a namespace prefix, followed by a slash and a sidebar name. The name should include only lowercase alphanumeric characters or dashes, and start with a letter. Example: `my-plugin/my-custom-sidebar`.
 - a `settings` object, containing a title and a render function. 
 
-This method only registers a sidebar. To open the sidebar, use the `__experimentalRegisterSidebar` method below.
+This method only registers a sidebar. To open the sidebar, use the `__experimentalActivateSidebar` method below.
 
 #### Example: