Document the ChannelBindings class

This commit documents the ChannelBindings class.

Part of #9

Author: DirectXMan12

gssapi/raw/chan_bindings.pyx

@@ -3,6 +3,11 @@ from libc.stdlib cimport calloc, free
 from gssapi.raw.cython_types cimport *
 
 cdef class ChannelBindings:
+    """GSSAPI Channel Bindings
+
+    This class represents a set of GSSAPI channel bindings.
+    """
+
     # defined in pxd file
     # cdef public object initiator_address_type
     # cdef public bytes initiator_address
@@ -15,6 +20,15 @@ cdef class ChannelBindings:
     def __init__(ChannelBindings self, initiator_address_type=None,
                  initiator_address=None, acceptor_address_type=None,
                  acceptor_address=None, application_data=None):
+        """
+        Args:
+            initiator_address_type (AddressType): the initiator address type
+            initiator_address (bytes): the initiator address
+            acceptor_address_type (AddressType):  the acceptor address type
+            acceptor_address (bytes): the acceptor address
+            application_data (bytes): additional application-specific data
+        """
+
         self.initiator_address_type = initiator_address_type
         self.initiator_address = initiator_address
 
@@ -24,6 +38,7 @@ cdef class ChannelBindings:
         self.application_data = application_data
 
     cdef gss_channel_bindings_t __cvalue__(ChannelBindings self) except NULL:
+        """Get the C struct version of the channel bindings"""
         cdef gss_channel_bindings_t res
         res = <gss_channel_bindings_t>calloc(1, sizeof(res[0]))