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.
Obvious typos around `diff-type` were fixed.
An obvious extra use of diff blocks was removed.
## Review
A dedicated reviewer checked the rule description successfully for:
- [x] logical errors and incorrect information
- [x] information gaps and missing content
- [x] text style and tone
- [x] PR summary and labels follow [the
guidelines](https://github.com/SonarSource/rspec/#to-modify-an-existing-rule)
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Co-authored-by: hendrik-buchwald-sonarsource <64110887+hendrik-buchwald-sonarsource@users.noreply.github.com>
