Added documentation for exceptions raised by elasticsearch-py

Fixes #58, thanks, willkg, for the report!

elasticsearch/exceptions.py

@@ -1,24 +1,39 @@
 __all__ = [
     'ImproperlyConfigured', 'ElasticsearchException', 'SerializationError',
-    'TransportError', 'NotFoundError', 'ConflictError', 'RequestError'
+    'TransportError', 'NotFoundError', 'ConflictError', 'RequestError', 'ConnectionError'
 ]
 
 class ImproperlyConfigured(Exception):
-    pass
+    """
+    Exception raised when the config passed to the client is inconsistent or invalid.
+    """
 
 class ElasticsearchException(Exception):
-    pass
+    """
+    Base class for all exceptions raised by this package's operations (doesn't
+    apply to :class:`~elasticsearch.ImproperlyConfigured`).
+    """
 
 
 class SerializationError(ElasticsearchException):
-    pass
+    """
+    Data passed int failed to serialize properly in the ``Serializer`` being
+    used.
+    """
 
 
 class TransportError(ElasticsearchException):
-    """ Exception raised when ES returns a non-OK (>=400) HTTP status code. """
+    """
+    Exception raised when ES returns a non-OK (>=400) HTTP status code. Or when
+    an actual connection error happens; in that case the ``status_code`` will
+    be set to ``'N/A'``.
+    """
     @property
     def status_code(self):
-        """ The HTTP status code of the response that precipitated the error. """
+        """
+        The HTTP status code of the response that precipitated the error or
+        ``'N/A'`` if not applicable.
+        """
         return self.args[0]
 
     @property
@@ -28,7 +43,7 @@ class TransportError(ElasticsearchException):
 
     @property
     def info(self):
-        """ Dict of returned error info from ES, where applicable. """
+        """ Dict of returned error info from ES, where available. """
         return self.args[2]
 
     def __str__(self):
@@ -36,22 +51,26 @@ class TransportError(ElasticsearchException):
 
 
 class ConnectionError(TransportError):
-    """ Error raised when there was an exception while talking to ES. """
+    """
+    Error raised when there was an exception while talking to ES. Original
+    exception from the underlying :class:`~elasticsearch.Connection`
+    implementation is available as ``.info.``
+    """
     def __str__(self):
         return 'ConnectionError(%s) caused by: %s(%s)' % (
             self.error, self.info.__class__.__name__, self.info)
 
 
 class NotFoundError(TransportError):
-    pass
+    """ Exception representing a 404 status code. """
 
 
 class ConflictError(TransportError):
-    pass
+    """ Exception representing a 409 status code. """
 
 
 class RequestError(TransportError):
-    pass
+    """ Exception representing a 400 status code. """
 
 # more generic mappings from status_code to python exceptions
 HTTP_EXCEPTIONS = {