Massage SSHClient.connect exception-raising docstring

- Sphinx Python domain can link to non-stdlib exception classes inside
  the `:raises:` fieldlist now! yay!!
- Add explicit mention of 'can raise NoValidConnectionsError', which was
  never added when the latter was created. Was still technically correct
  (it is a subclass of socket.error) but that is not the best kind of
  correct, after all.

1 files changed, 13 insertions, 8 deletions

diff --git a/paramiko/client.py b/paramiko/client.py
index 5667d7e7..e9bcfb56 100644
--- a/paramiko/client.py
+++ b/paramiko/client.py
@@ -321,14 +321,19 @@ class SSHClient(ClosingContextManager):
             `.Transport` instance to be used by this client. Defaults to
             `.Transport.__init__`.
 
-        :raises:
-            `.BadHostKeyException` -- if the server's host key could not be
-            verified
-        :raises: `.AuthenticationException` -- if authentication failed
-        :raises:
-            `.SSHException` -- if there was any other error connecting or
-            establishing an SSH session
-        :raises socket.error: if a socket error occurred while connecting
+        :raises BadHostKeyException:
+            if the server's host key could not be verified.
+        :raises AuthenticationException: if authentication failed.
+        :raises socket.error:
+            if a socket error (other than connection-refused or
+            host-unreachable) occurred while connecting.
+        :raises NoValidConnectionsError:
+            if all valid connection targets for the requested hostname (eg IPv4
+            and IPv6) yielded connection-refused or host-unreachable socket
+            errors.
+        :raises SSHException:
+            if there was any other error connecting or establishing an SSH
+            session.
 
         .. versionchanged:: 1.15
             Added the ``banner_timeout``, ``gss_auth``, ``gss_kex``,