Marco Borgeaud 4aee7ce2d6
Diff blocks: fix incorrect use for swift (#2805)
Improvement identified in #2790.

Add a prefix to the diff-id when it is used multiple times in different
"how to fix it in XYZ" sections to avoid ambiguity and pedantically
follow the spec:

> A single and unique diff-id should be used only once for each type of
code example as shown in the description of a rule.
2023-08-15 11:52:10 +02:00
..