message: docs: fix typo in IR.md
diff: @@ -219,7 +219,7 @@ A name belonging to the Value namespace may appear in multiple places, namely as
  A value name used in a graph must have a unique definition site, with the exception that the same name MAY appear in both the graph input list and graph initializer list. (Further exceptions apply in the presence of nested subgraphs, as described later.)
  -When a name appears in both the initializer list and the graph input list, a runtime MAY allow a caller to specify a value for this (input) name overriding the value specified in the initializer and a runtime MAY allow users to omit specifying a value for this (input) name, choosing the value specified in the initializer. Names of constants that are not meant to overridden by the caller should appear only in the initializer list and not in the graph input list. In nested subgraphs used as attribute values, users MUST NOT use the same name as both a subgraph initializer and subgraph input (unless the corresponding op's specification explicitly allows it).
  +When a name appears in both the initializer list and the graph input list, a runtime MAY allow a caller to specify a value for this (input) name overriding the value specified in the initializer and a runtime MAY allow users to omit specifying a value for this (input) name, choosing the value specified in the initializer. Names of constants that are not meant to be overridden by the caller should appear only in the initializer list and not in the graph input list. In nested subgraphs used as attribute values, users MUST NOT use the same name as both a subgraph initializer and subgraph input (unless the corresponding op's specification explicitly allows it).
  Edges in the computation graph are established by outputs of one node being referenced by name in the inputs of a subsequent node.
  