EssentialsDocumentComponent and EssentialsContentComponent javadoc is incorrect

Both components refer to each other, even though they are unrelated. The both inherit directly form CommonComponent. Additionally EssentialsDocumentComponent promises to put the sitemapitem mapped document on the path if no document path is specified. Except it doesn't do this at all.

These are documentation errors, but at least the DocumentComponent is making a promise it doesn't keep.

Also update https://documentation.bloomreach.com/library/setup/hst-components/document-component.html