Update README

Author: saketkc

README.md

@@ -12,6 +12,24 @@ After you get a copy of the source code, please change into the directory where
 python setup.py install
 ```
 
+This will install the following packages. If some of these are already present, 
+they might be replaced by the designated version. So we strongly recommend
+creating a separate enrivoment (using `venv` or `conda`) before installing
+`ribotricer`.
+
+```
+pyfaidx>=0.5.0
+pysam>=0.11.2.2
+numpy>=1.11.0
+pandas>=0.20.3
+scipy>=0.19.1
+matplotlib>=2.1.0
+click>=6.0
+click-help-colors>=0.3
+quicksect>=0.2.0
+tqdm>=4.23.4
+```
+
 ------------------
 
 ## Workflow of ribotricer