Fix natspec comment missing * (#5136)

contracts/utils/structs/Heap.sol

@@ -218,7 +218,7 @@ library Heap {
         }
     }
 
-    /*
+    /**
      * @dev Swap node `i` and `j` in the tree.
      */
     function _swap(Uint256Heap storage self, uint64 i, uint64 j) private {
@@ -485,7 +485,7 @@ library Heap {
         }
     }
 
-    /*
+    /**
      * @dev Swap node `i` and `j` in the tree.
      */
     function _swap(Uint208Heap storage self, uint24 i, uint24 j) private {

scripts/generate/templates/Heap.js

@@ -220,7 +220,7 @@ function clear(${struct} storage self) internal {
     }
 }
 
-/*
+/**
  * @dev Swap node \`i\` and \`j\` in the tree.
  */
 function _swap(${struct} storage self, ${indexType} i, ${indexType} j) private {