Remove sidebar metadata from page-elements.mdx

Removed sidebar label and position metadata from page elements documentation.

Author: alexluckett

docs/features/page-elements.mdx

@@ -1,8 +1,3 @@
----
-sidebar_label: "Page Elements"
-sidebar_position: 2
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-
 # Page Elements
 
 For each page it renders, the plugin computes a set of view model properties and makes them available to your base layout template — set via `baseLayoutPath` in the [plugin options](../plugin-options.md#nunjucks-configuration). Some of these map directly to GOV.UK Frontend components (back link, phase banner, error summary, service navigation). Others are general metadata about the current page or form (title, name, slug) that your layout can use however it needs to.