Update sign-in-out.md

Revised page to address Issue #355 (add site specification on sign in)

Author: dzucker-tab

Diff for: docs/sign-in-out.md

@@ -3,37 +3,42 @@ title: Sign In and Out
 layout: docs
 ---
 
-To sign in and out of Tableau Server, call the `Auth.sign_in` and `Auth.sign_out` functions like so:
+To sign in and out of Tableau Server, call the server's `.auth.signin` method in a`with` block.
 
 ```py
 import tableauserverclient as TSC
 
-tableau_auth = TSC.TableauAuth('USERNAME', 'PASSWORD')
-server = TSC.Server('http://SERVER_URL')
+tableau_auth = TSC.TableauAuth('USERNAME', 'PASSWORD', `SITENAME`)
+server = TSC.Server('https://SERVER_URL')
 
-server.auth.sign_in(tableau_auth)
+with server.auth.sign_in(tableau_auth):
+    # Do awesome things here!
+```
 
-# Do awesome things here!
+The `SERVER_URL` is the URL of the Tableau server without subpaths. For local Tableau servers, in the form of: `https://www.MY_SERVER.com`. For Tableau Online, `https://10ax.online..tableau.com/`.
 
-server.auth.sign_out()
-```
+`SITENAME` is same as the `contentURL`, or site subpath, of your full site URL. This parameter can be omitted when signing in to the Default site of a locally installed Tableau server.
+
+Optionally, you can override the Tableau API version by adding `server.version = '<VERSION_NUMBER>'` before the `auth.signin` call. 
+
+The TSC library signs you out of Tableau Server when you exit out of the `with` block.
 
 <div class="alert alert-info">
-    <b>Note:</b> When you sign in, the TSC library manages the authenticated session for you, however it is still
-    limited by the maximum session length (of four hours) on Tableau Server.
+    <b>Note:</b> When you sign in, the TSC library manages the authenticated session for you, however the validity of the underlying 
+    credentials token is limited by the maximum session length set on your Tableau Server (2 hours by default).
 </div>
 
-
-Alternatively, for short programs, consider using a `with` block:
+An option to using a `with` block is to call the `Auth.sign_in` and `Auth.sign_out` functions explicitly.
 
 ```py
 import tableauserverclient as TSC
 
 tableau_auth = TSC.TableauAuth('USERNAME', 'PASSWORD')
 server = TSC.Server('http://SERVER_URL')
 
-with server.auth.sign_in(tableau_auth):
-    # Do awesome things here!
-```
+server.auth.sign_in(tableau_auth)
 
-The TSC library signs you out of Tableau Server when you exit out of the `with` block.
+# Do awesome things here!
+
+server.auth.sign_out()
+```