[llvm] ADT: Improve DenseMap documentation for insertion APIs (PR #172177)

[Jakub Kuderski via llvm-commits]

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@@ -295,14 +310,24 @@ class DenseMapBase : public DebugEpochBase {
     insert(adl_begin(R), adl_end(R));
   }
 
+  /// Inserts a new element or assigns to the existing one.
+  ///
+  /// If the key does not exist, a new element is inserted. If the key already
+  /// exists, the mapped value is replaced with the provided value.
+  ///
+  /// \param Key The key to insert or update.
+  /// \param Val The value to insert or assign.
+  /// \returns A pair consisting of an iterator to the element and a boolean
+  ///          indicating whether insertion took place.
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kuhar wrote:

similar here

https://github.com/llvm/llvm-project/pull/172177