Updating rocprofv3 doc for pc sampling beta option (#59)

* Updating rocprofv3 doc for pc sampling beta option

* Update source/docs/rocprofv3_input_schema.json

* Update using-rocprofv3.rst

---------

Co-authored-by: Elwazir, Ammar <Ammar.Elwazir@amd.com>

source/docs/rocprofv3_input_schema.json

@@ -156,6 +156,10 @@
                     "pc_sampling_interval": {
                          "type": "integer",
                          "description": "pc sampling interval"
+                    },
+                    "pc-sampling-beta-enabled": {
+                         "type": "boolean",
+                         "description": "enable pc sampling support; beta version"
                     }
                  }
               }