Add the changelog entry for the continue link

CHANGELOG.md

@@ -15,6 +15,7 @@ each change under the current top section as you work.
 
 ### Fixed
 - A student's **upcoming lessons no longer pile on top of each other**. On the booking page, the lesson name, its date and time, the status badge and the **Cancel** button could render over one another instead of sitting in a tidy row — worst with a long lesson-type name, and on narrow screens, where the row had no phone layout at all. The panel now keeps its shape whatever the theme around it does, long names wrap instead of shoving the Cancel button out of the row, and on a phone the lesson details stack above the buttons.
+- The registration page **no longer dead-ends a visitor who is already signed in**. It used to greet them with "You already have an account and are logged in." and nothing else, leaving them to find their own way to the studio. They now get a link onward to the page chosen under the block's **After registration** panel, and the link names it — "Continue to Book a Lesson" rather than the vaguer wording an invited student used to see. With no page chosen, the message appears on its own as before, because sending someone who is already signed in to the sign-in screen helps nobody.
 
 ## [1.2.3]