Added install from requirements file into README

README.md

@@ -23,6 +23,20 @@ Other python versions maybe not **supported** at the moment.
 
 ##Dependencies:
 
+Sublist3r depends on the `requests`, `dnspython` and `argparse` python modules. These dependencies can be installed using the requirements file:
+- Installation on Windows:
+
+```
+c:\python27\python.exe -m pip install -r requirements.txt
+```
+
+- Installation on Linux
+```
+sudo pip install -r requirements.txt
+```
+
+Alternatively, each module can be installed independently as shown below.
+
 ####Requests library (http://docs.python-requests.org/en/latest/)
 
 - Install for Windows: