DOC Document API that is being removed (#624)

Author: GuySartorelli

en/08_Changelogs/5.4.0.md

@@ -164,6 +164,8 @@ The changes include:
 - [`SSTemplateParser`](api:SilverStripe\View\SSTemplateParser) has been deprecated. It will be renamed to `SilverStripe\TemplateEngine\SSTemplateParser`.
 - [`TemplateIteratorProvider`](api:SilverStripe\View\TemplateIteratorProvider) has been deprecated. It will be renamed to `SilverStripe\TemplateEngine\TemplateIteratorProvider`.
 - [`TemplateParser`](api:SilverStripe\View\TemplateParser) has been deprecated. It will be renamed to `SilverStripe\TemplateEngine\TemplateParser`.
+- [`ElementalAreaController::removeNamespacesFromFields()`](api:DNADesign\Elemental\Controllers\ElementalAreaController::removeNamespacesFromFields()) has been deprecated. It will be removed without equivalent functionality to replace it.
+- [`BaseElement::updateFromFormData()`](api:DNADesign\Elemental\Models\BaseElement::updateFromFormData()) has been deprecated. It will be removed without equivalent functionality to replace it.
 
 ## Bug fixes