Document 'ssl_minimum_version' use-cases

docs/advanced-usage.rst

@@ -357,6 +357,38 @@ the ``key_password`` parameter to specify a password to decrypt the key.
 
 If your key isn't encrypted the ``key_password`` parameter isn't required.
 
+TLS minimum and maximum versions
+--------------------------------
+
+When the configured TLS versions by urllib3 aren't compatible with the TLS versions that
+the server is willing to use you'll likely see an error like this one:
+
+.. code-block::
+
+    SSLError(1, '[SSL: UNSUPPORTED_PROTOCOL] unsupported protocol (_ssl.c:1124)')
+
+Starting in v2.0 by default urllib3 uses TLS 1.2 and later so servers that only support TLS 1.1
+or earlier will not work by default with urllib3.
+
+To fix the issue you'll need to use the ``ssl_minimum_version`` option along with the `TLSVersion enum`_
+in the standard library ``ssl`` module to configure urllib3 to accept a wider range of TLS versions.
+
+For the best security it's a good idea to set this value to the version of TLS that's being used by the
+server. For example if the server requires TLS 1.0 you'd configure urllib3 like so:
+
+.. code-block:: python
+    
+    import ssl
+    import urllib3
+    
+    http = urllib3.PoolManager(
+        ssl_minimum_version=ssl.TLSVersion.TLSv1
+    )
+    # This request works!
+    resp = http.request("GET", "https://tls-v1-0.badssl.com:1010")
+
+.. _TLSVersion enum: https://docs.python.org/3/library/ssl.html#ssl.TLSVersion
+
 .. _ssl_mac:
 .. _certificate_validation_and_mac_os_x:
 

docs/v2-roadmap.rst

@@ -55,7 +55,7 @@ over the wire.
 
 If you still need to use TLS 1.0 or 1.1 in your application
 you can still upgrade to v2.0, you'll only need to set
-``ssl_version`` to the proper values to continue using
+``ssl_minimum_version`` to the proper value to continue using
 legacy TLS versions.