[DOC] Add notes in pyarpack documentation. (#364)

EXAMPLES/PYARPACK/README

@@ -5,11 +5,15 @@ Installation:
 
 Python3: ~/arpack-ng/build> cmake -DCMAKE_INSTALL_PREFIX=/tmp/local -DPYTHON3=ON -DBOOST_PYTHON_LIBSUFFIX="3" ..
          ~/arpack-ng/build> make all test
+         ~/arpack-ng/build> make install
 Note: Boost must have been compiled for Python3.
+Note: installation will install libpyarpack.so in the install directory.
 
 Usage:
 ------
 
+PYTHONPATH must include the directory where libpyarpack.so has been installed.
+
 >> export PYTHONPATH="/tmp/local/lib/pyarpack:${PYTHONPATH}"
 >> python
 >> import pyarpack

README.md

@@ -41,6 +41,7 @@ Important Features:
     $ ./configure --with-blas=mkl_gf_ilp64 --with-lapack=mkl_gf_ilp64
     $ make all check```
 * pyarpack: python support based on Boost.Python.Numpy exposing C++ API.
+  Check out ./EXAMPLES/PYARPACK/README for more details.
 
 This project started as a joint project between Debian, Octave and Scilab in order to
 provide a common and maintained version of arpack.