extension.rdoc: RB_TYPE_P [ci skip]

* doc/extension.rdoc, doc/extension.rdoc (Checking Data Types):
  [DOC] mention RB_TYPE_P.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55042 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

doc/extension.ja.rdoc

@@ -1223,6 +1223,7 @@ Data_Get_Struct(data, type, sval) ::
 
 == 型チェック
 
+  RB_TYPE_P(value, type)
   TYPE(value)
   FIXNUM_P(value)
   NIL_P(value)

doc/extension.rdoc

@@ -1145,6 +1145,10 @@ Data_Get_Struct(data, type, sval) ::
 
 == Checking Data Types
 
+RB_TYPE_P(value, type) ::
+
+  Is +value+ an internal type (T_NIL, T_FIXNUM, etc.)?
+
 TYPE(value) ::
 
   Internal type (T_NIL, T_FIXNUM, etc.)