fixed sample.json files(added missing comma) (#1649)

Author: amakarev

DirectProgramming/C++SYCL/DenseLinearAlgebra/guided_simpleCudaGraphs_SYCLMigration/sample.json

@@ -19,6 +19,6 @@
                  ]
         }]
 
-  }
+  },
   "expertise": "Concept and Functionality"
 }

DirectProgramming/C++SYCL/MapReduce/guided_quasirandomGenerator_SYCLMigration/sample.json

@@ -20,6 +20,6 @@
                  ]
         }]
 
-  }
+  },
   "expertise": "Code Optimization"
 }

DirectProgramming/C++SYCL/guided_convolutionSeparable_SYCLmigration/sample.json

@@ -22,6 +22,6 @@
                  ]
         }]
 
-  }
+  },
   "expertise": "Code Optimization"
 }