[Functions] Fix functions comments (#1126)

* fix functions comments

* Add paddle lite backend

examples/text/ernie-3.0/cpp/seq_cls_infer.cc

@@ -63,6 +63,7 @@ bool CreateRuntimeOption(fastdeploy::RuntimeOption* option) {
 
   if (FLAGS_device == "kunlunxin") {
     option->UseKunlunXin();
+    option->UsePaddleLiteBackend();
     return true;
   } else if (FLAGS_device == "gpu") {
     option->UseGpu();

fastdeploy/function/transpose.h

@@ -17,6 +17,10 @@
 #include "fastdeploy/core/fd_tensor.h"
 
 namespace fastdeploy {
+
+/** \brief All C++ FDTensor Operation APIs are defined inside this namespace
+ *
+ */
 namespace function {
 /** Excute the transpose operation for input FDTensor along given dims.
     @param x The input tensor.