update readme

README.md

@@ -1,14 +1,16 @@
-# Install pygpg
+# Python binding for Grasp Pose Generator (pyGPG)
+
+## Install
 - Install gpg
 ```
 git clone https://github.com/atenpas/gpg.git
 cd gpg && mkdir build && cd build && cmake .. && make
 sudo make install
 ```
-- Install Python 3.7:
+- Install Python 3.7(optional):
 `sudo apt install python3.7-dev`
 
-- Then run command (in Python 3.7 environment):
+- Install pygpg
 ```
 git clone https://github.com/lianghongzhuo/pygpg.git
 cd pygpg
@@ -22,3 +24,7 @@ import pygpg
 points = [put your point cloud here, should be a nX3 numpy array]
 grasps = pygpg.generate_grasps(points)
 ```
+
+## Known issues:
+- pcl default will add python2.7 path in to the system https://github.com/pybind/pybind11/issues/1637#issuecomment-557609822
+  So we need to hard code witch python to use in cmake file to avoid the pybind binding python2.7 with gpg.