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diff --git a/src/tools/clippy/src/docs/collapsible_match.txt b/src/tools/clippy/src/docs/collapsible_match.txt
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+### What it does
+Finds nested `match` or `if let` expressions where the patterns may be "collapsed" together
+without adding any branches.
+
+Note that this lint is not intended to find _all_ cases where nested match patterns can be merged, but only
+cases where merging would most likely make the code more readable.
+
+### Why is this bad?
+It is unnecessarily verbose and complex.
+
+### Example
+```
+fn func(opt: Option<Result<u64, String>>) {
+    let n = match opt {
+        Some(n) => match n {
+            Ok(n) => n,
+            _ => return,
+        }
+        None => return,
+    };
+}
+```
+Use instead:
+```
+fn func(opt: Option<Result<u64, String>>) {
+    let n = match opt {
+        Some(Ok(n)) => n,
+        _ => return,
+    };
+}
+```
+\ No newline at end of file