Add link to docs section

Author: burnash

README.md

@@ -152,35 +152,29 @@ for cell in cell_list:
 worksheet.update_cells(cell_list)
 ```
 
-## Requirements
-
-Python 2.6+ or Python 3+
-
 ## Installation
 
-### From GitHub
+### Requirements
 
-```sh
-git clone https://github.com/burnash/gspread.git
-cd gspread
-python setup.py install
-```
+Python 2.6+ or Python 3+
 
 ### From PyPI
 
 ```sh
 pip install gspread
 ```
 
-If you're on easy_install, it's:
+### From GitHub
 
 ```sh
-easy_install gspread
+git clone https://github.com/burnash/gspread.git
+cd gspread
+python setup.py install
 ```
 
 ## Documentation
-
-[API Reference](http://gspread.readthedocs.org/)
+* [Getting Google API's credentials](http://gspread.readthedocs.io/en/latest/oauth2.html)
+* [gspread API Reference](http://gspread.readthedocs.org/)
 
 ## Testing