try fix logical op doc

Author: yi.wu

paddle/fluid/operators/logical_op.cc

@@ -136,16 +136,16 @@ class LogicalOp : public framework::OperatorWithKernel {
       ::paddle::operators::UnaryLogicalOpInferShape<_##op_type##Comment>, \
       ::paddle::framework::EmptyGradOpMaker);
 
-REGISTER_BINARY_LOGICAL_OP(logical_and, "$$Out = X \\&\\& Y$$");
+REGISTER_BINARY_LOGICAL_OP(logical_and, " $$Out = X \\&\\& Y$$");
 REGISTER_BINARY_LOGICAL_KERNEL(logical_and, CPU,
                                paddle::operators::LogicalAndFunctor);
-REGISTER_BINARY_LOGICAL_OP(logical_or, "$$Out = X || Y$$");
+REGISTER_BINARY_LOGICAL_OP(logical_or, " $$Out = X || Y$$");
 REGISTER_BINARY_LOGICAL_KERNEL(logical_or, CPU,
                                paddle::operators::LogicalOrFunctor);
-REGISTER_UNARY_LOGICAL_OP(logical_not, "$$Out = !X$$");
+REGISTER_UNARY_LOGICAL_OP(logical_not, " $$Out = !X$$");
 REGISTER_UNARY_LOGICAL_KERNEL(logical_not, CPU,
                               paddle::operators::LogicalNotFunctor);
 REGISTER_BINARY_LOGICAL_OP(logical_xor,
-                           "$$Out = (X || Y) \\, \\&\\& \\, !(X \\&\\& Y)$$");
+                           " $$Out = (X || Y) \\&\\& !(X \\&\\& Y)$$");
 REGISTER_BINARY_LOGICAL_KERNEL(logical_xor, CPU,
                                paddle::operators::LogicalXorFunctor);