update installation procedure in doc

docs/source/installation.rst

@@ -4,17 +4,25 @@ Installation
 
 NeuTomPy toolbox supports **Linux**, **Windows** and **Mac OS** 64-bit operating systems.
 
-First of all, install a `Conda <https://www.anaconda.com/download/>`_  python environment with **Python 3.5 or 3.6**.
+First of all, install a `Conda <https://www.anaconda.com/download/>`_  python environment with **Python 3.6** and then activate it:
 
-It is required to install some dependencies, hence run the following inside a ``conda`` environment:
+.. code-block:: bash
+
+    conda create -n ntp_env python=3.6 
+    conda activate ntp_env
+
+Install some dependencies:
 
 .. code-block:: bash
 
     conda install -c simpleitk simpleitk
+    conda install scikit-image
+    conda install ipython numexpr astropy tifffile mkl_fft tqdm
     conda install -c astra-toolbox astra-toolbox
-    conda install -c conda-forge ipython numpy numexpr matplotlib astropy tifffile opencv scikit-image read-roi mkl_fft scipy six tqdm pywavelets
+    pip install opencv-python read-roi
+    pip install -U numpy
 
-Then install NeuTomPy toolbox via ``pip``:
+Finally, install NeuTomPy toolbox via ``pip``:
 
 .. code-block:: bash