[MXNET-1164] Generate the document for cpp-package using Doxygen (apa…

…che#12977)

* Adding cpp-package directory to the Doxyfile. Updating the index.md file in c++ api directory.

* Updating the link to classes in C++ API to point to correct html file.

* Updated the links to use relative paths.

* Removed the extra slash character in the url

* Excluded the 3rdparty folder as per the review comment.

cpp-package/scripts/OpWrapperGenerator.py

@@ -223,14 +223,14 @@ def GetOpDefinitionString(self, use_name, indent=0):
             if arg.isEnum and use_name:
                 # comments
                 ret = ret + self.GenDescription(arg.description, \
-                                        '/*! \\breif ', \
+                                        '/*! \\brief ', \
                                         ' *        ')
                 ret = ret + " */\n"
                 # definition
                 ret = ret + arg.enum.GetDefinitionString(indent) + '\n'
         # create function comments
         ret = ret + self.GenDescription(self.description, \
-                                        '/*!\n * \\breif ', \
+                                        '/*!\n * \\brief ', \
                                         ' *        ')
         for arg in self.args:
             if arg.name != 'symbol_name' or use_name:

docs/Doxyfile

@@ -770,7 +770,7 @@ WARN_LOGFILE           =
 # spaces.
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = include src/common
+INPUT                  = include src/common cpp-package/include/mxnet-cpp
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
@@ -805,7 +805,7 @@ RECURSIVE              = YES
 # Note that relative paths are relative to the directory from which doxygen is
 # run.
 
-EXCLUDE                =
+EXCLUDE                = 3rdparty
 
 # The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
 # directories that are symbolic links (a Unix file system feature) are excluded

docs/api/c++/index.md

@@ -1,8 +1,55 @@
 # MXNet - C++ API
 
+The MXNet C++ Package provides C++ API bindings to the users of MXNet.  Currently, these bindings are not available as standalone package.
+The users of these bindings are required to build this package as mentioned below.
+
+## Building C++ Package
+
+The cpp-package directory contains the implementation of C++ API. As mentioned above, users are required to build this directory or package before using it.
+**The cpp-package is built while building the MXNet shared library, *libmxnet.so*.**
+
+### Steps to build the C++ package:
+1.  Building the MXNet C++ package requires building MXNet from source.
+2.  Clone the MXNet GitHub repository **recursively** to ensure the code in submodules is available for building MXNet.
+	```
+	git clone --recursive https://github.com/apache/incubator-mxnet mxnet
+	```
+
+3.  Install the [prerequisites](<https://mxnet.incubator.apache.org/install/build_from_source#prerequisites>), desired [BLAS libraries](<https://mxnet.incubator.apache.org/install/build_from_source#blas-library>) and optional [OpenCV, CUDA, and cuDNN](<https://mxnet.incubator.apache.org/install/build_from_source#optional>) for building MXNet from source.
+4.  There is a configuration file for make, [make/config.mk](<https://github.com/apache/incubator-mxnet/blob/master/make/config.mk>) that contains all the compilation options. You can edit this file and set the appropriate options prior to running the **make** command.
+5.  Please refer to  [platform specific build instructions](<https://mxnet.incubator.apache.org/install/build_from_source#build-instructions-by-operating-system>) and available [build configurations](https://mxnet.incubator.apache.org/install/build_from_source#build-configurations) for more details.
+5.  For enabling the build of C++ Package, set the **USE\_CPP\_PACKAGE = 1** in [make/config.mk](<https://github.com/apache/incubator-mxnet/blob/master/make/config.mk>). Optionally, the compilation flag can also be specified on **make** command line as follows.
+	```
+	make -j USE_CPP_PACKAGE=1
+	```
+
+## Usage
+
+In order to consume the C++ API please follow the steps below.
+
+1. Ensure that the MXNet shared library is built from source with the **USE\_CPP\_PACKAGE = 1**.
+2. Include the [MxNetCpp.h](<https://github.com/apache/incubator-mxnet/blob/master/cpp-package/include/mxnet-cpp/MxNetCpp.h>) in the program that is going to consume MXNet C++ API.
+	```
+	#include <mxnet-cpp/MxNetCpp.h>
+	```
+3. While building the program, ensure that the correct paths to the directories containing header files and MXNet shared library.
+4. The program links the MXNet shared library dynamically. Hence the library needs to be accessible to the program during runtime. This can be achieved by including the path to the shared library in the environment variable  **LD\_LIBRARY\_PATH** for Linux, Mac. and Ubuntu OS and **PATH** for Windows OS.
+
+
+## Tutorial
+
+A basic tutorial can be found at <https://mxnet.incubator.apache.org/tutorials/c++/basics.html>.
+
+## Examples
+
+The example directory contains examples for you to get started.
 For namespaces, classes, and code files for the MXNet C++ package, see the  following:
 
-* [Namespaces](http://mxnet.io/doxygen/namespaces.html)
-* [Classes](http://mxnet.io/doxygen/annotated.html)
-* [Code Files](http://mxnet.io/doxygen/files.html)
-* [MXNet CPP Package](https://github.com/dmlc/mxnet/tree/master/cpp-package)
+## Links to the documentation
+
+The classes and functions in MXNet C++ API are available under **mxnet::cpp** namespace. The links to the documenation are as follows:
+
+1. [Namespaces](../../doxygen/namespaces.html)
+2. [Classes in mxnet::cpp namespace](../../doxygen/namespacemxnet_1_1cpp.html)
+3. [Code Files](../../doxygen/files.html)
+4. [MXNet CPP Package](https://github.com/dmlc/mxnet/tree/master/cpp-package)