Export of internal Abseil changes

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90e177c9e8bdfb38eed84d2377b019353c3990f8 by Abseil Team <absl-team@google.com>:

Fix typo in documentation.

PiperOrigin-RevId: 341814490
GitOrigin-RevId: 90e177c9e8bdfb38eed84d2377b019353c3990f8
Change-Id: Ia84bf687921caedf1d8fab243c7383835d305e44

absl/container/flat_hash_set.h

@@ -324,7 +324,7 @@ class flat_hash_set
 
   // flat_hash_set::merge()
   //
-  // Extracts elements from a given `source` flat hash map into this
+  // Extracts elements from a given `source` flat hash set into this
   // `flat_hash_set`. If the destination `flat_hash_set` already contains an
   // element with an equivalent key, that element is not extracted.
   using Base::merge;