I’d like to add static HTML to the top of desk.html / workspace, just above the Onboarding section of my custom App. This static HTML is nothing other than a few notes about the app.
Workspace in v14 does provide a Header and a Text block, however these are very limited in their content and formatting. Adding any HTML or even escape sequences such as \t or \n to either of the Header or Text block is ignored.
A workaround as of v14.6, is to create either a Shortcut or a Card block and to assign a new row to it of type Page, and then create (and link) a new HTML Page document.