Add nested cloze limit to manual

Fix: ankitects#313

src/editing.md

@@ -401,6 +401,10 @@ The inner cloze is entirely nested within the outer. There is no support for par
 
 with the word "was" appearing in both deletions.
 
+In version 24.11 nested cloze deletions have been limited to a maximum of three levels.
+This change had been introduced in [PR #3264](https://github.com/ankitects/anki/pull/3264) to prevent
+slowdowns to the point of crashing anki.
+
 Prior to version 2.1.56, if you need to create clozes from overlapping text, add another Text
 field to your cloze, add it to the [template](templates/intro.md), and then when
 creating notes, paste the text into two separate fields, like so: