Update README

Author: vbkaisetsu

README.md

@@ -41,8 +41,9 @@ $ pip3 install primitiv [--user]
 To enable CUDA and/or OpenCL support, specify `--enable-cuda` or
 `--enable-opencl` with `--global-option` flag.
 
-Eigen is bundled with the package contained in PyPI. Use `--disable-eigen` flag,
-if you want to disable `Eigen` device.
+`--enable-eigen` flag that enables `Eigen` backend is added by default in the
+package contained in PyPI. To disable the Eigen backend, use `--disable-eigen`
+flag. Note that Eigen is bundled with the package contained in PyPI.
 
 We are providing only a source pacakge for now, and `pip` command
 downloads the source package and builds it before installing.

package_description.rst

@@ -41,8 +41,11 @@ Build and install primitiv with CUDA and/or OpenCL support::
     # Enable both CUDA and OpenCL
     pip3 install primitiv --global-option --enable-cuda --global-option --enable-opencl
 
-Eigen is bundled with the package contained in PyPI. Use ``--disable-eigen`` flag,
-if you want to disable ``Eigen`` device.
+``--enable-eigen`` flag that enables ``Eigen`` backend is added by default in
+the package contained in PyPI. To disable the Eigen backend, use
+``--disable-eigen`` flag. Note that Eigen is bundled with the package contained
+in PyPI.
+
 
 Notes
 -----