updated pip instructions. added doc link.

Author: jlwalke2

README.md

@@ -17,6 +17,9 @@
 
 </div>
 
+
+###### Full documentation:  https://sassoftware.github.io/python-sasctl/index.html
+
 ## Overview
 
 The sasctl package enables easy communication between the SAS Viya 
@@ -39,19 +42,19 @@ If not already present, these packages will be downloaded and installed automati
 
 The following additional packages are recommended for full functionality:
 - swat
-- kerberos / winkerberos
-
+- kerberos
 
-All required and recommended packages are listed in `requirements.txt` and can be installed easily with 
-```
-pip install -r requirements.txt
-```
 
 ### Installation
 
 ```
 pip install sasctl
 ```
+
+Functionality that depends on additional packages can be installed using the following:
+ - `pip install sasctl[swat]`
+ - `pip install sasctl[kerberos]`
+ - `pip install sasctl[all]`
 
 
 ## Getting Started