Add installation instructions

readme.md

 #  nd2 to tif conversion tools
 
+## Installation
+
+1. Download and install [miniconda3](https://docs.conda.io/en/latest/miniconda.html)
+2. Create new environment with python 3.8
+  - `conda create -n nd2 python=3.8`
+  - `conda activate nd2`
+3. Install the package `pip install -U git+https://gitlab.pasteur.fr/aaristov/nd2shrink.git`
+
+
 ## Compress nd2 to tif with 4x binning and 16 to 8 bits conversion
 
 ### Use:
@@ -10,7 +19,7 @@
 
 ### Use
 
-`python -m nd2_combine folder`
+`python -m nd2_combine path_to_folder`
 
 #### Input: