chore: remove old docs reference

Author: stern-shawn

CONTRIBUTING.md

@@ -22,7 +22,7 @@ it can be.
 ## <a name="question"></a> Got an API/Product Question or Problem?
 
 If you have questions about how to use `twilio-python`, please see our
-[docs][docs-link], and if you don't find the answer there, please contact
+[docs](./README.md), and if you don't find the answer there, please contact
 [[email protected]](mailto:[email protected]) with any issues you have.
 
 ## <a name="issue"></a> Found an Issue?
@@ -69,10 +69,6 @@ you're working on.
 For large fixes, please build and test the documentation before submitting the
 PR to be sure you haven't accidentally introduced layout or formatting issues.
 
-If you want to help improve the docs at
-[https://www.twilio.com/docs/libraries/python][docs-link], please contact
-[[email protected]](mailto:[email protected]).
-
 ## <a name="submit"></a> Submission Guidelines
 
 ### Submitting an Issue
@@ -162,6 +158,5 @@ There exists a separate `requirements.txt` document under `tests` that contains
 make test-install test
 ```
 
-[docs-link]: https://www.twilio.com/docs/libraries/python
 [issue-link]: https://github.com/twilio/twilio-python/issues/new
 [github]: https://github.com/twilio/twilio-python

advanced-examples/custom-http-client.md

@@ -1,6 +1,6 @@
 # Custom HTTP Clients for the Twilio Python Helper Library
 
-If you are working with the [Twilio Python Helper Library](/docs/libraries/python), and you need to be able to modify the HTTP requests that the library makes to the Twilio servers, you’re in the right place. The most common reason for altering the HTTP request is to connect and authenticate with an enterprise’s proxy server. We’ll provide sample code that you can use in your app to handle this and other use cases.
+If you are working with the Twilio Python Helper Library, and you need to be able to modify the HTTP requests that the library makes to the Twilio servers, you’re in the right place. The most common reason for altering the HTTP request is to connect and authenticate with an enterprise’s proxy server. We’ll provide sample code that you can use in your app to handle this and other use cases.
 
 ## Connect and authenticate with a proxy server