Tweak docs for gevent.pool. Fixes #1279.

doc/api/gevent.pool.rst

 :mod:`gevent.pool` -- Managing greenlets in a group
 ===================================================
 
-.. automodule:: gevent.pool
+.. module:: gevent.pool
+
+.. autoclass:: gevent.pool.Group
    :members:
-    :undoc-members:
    :inherited-members:
+
+   .. automethod:: __len__
+   .. automethod:: __contains__
+
+.. autoclass:: gevent.pool.PoolFull
+   :members:
+
+.. autoclass:: gevent.pool.Pool
+   :members:

doc/conf.py

@@ -71,7 +71,7 @@ master_doc = 'contents'
 
 # General information about the project.
 project = u'gevent'
-copyright = u'2009-2015, gevent contributors'
+copyright = u'2009-2018, gevent contributors'
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the

src/gevent/pool.py

@@ -289,10 +289,15 @@ class Group(GroupMappingMixin):
     they can be tested to see if they contain a greenlet, and they know the
     number (len) of greenlets they are tracking. If they are not tracking any
     greenlets, they are False in a boolean context.
+
+    .. attribute:: greenlet_class
+
+        Either :class:`gevent.Greenlet` (the default) or a subclass.
+        These are the type of
+        object we will :meth:`spawn`. This can be
+        changed on an instance or in a subclass.
     """
 
-    #: The type of Greenlet object we will :meth:`spawn`. This can be changed
-    #: on an instance or in a subclass.
     greenlet_class = Greenlet
 
     def __init__(self, *args):
@@ -524,10 +529,14 @@ class Pool(Group):
             maximum count of active greenlets that will be allowed in
             this pool. A few values have special significance:
 
-            * ``None`` (the default) places no limit on the number of
-              greenlets. This is useful when you need to track, but not limit,
-              greenlets, as with :class:`gevent.pywsgi.WSGIServer`. A :class:`Group`
-              may be a more efficient way to achieve the same effect.
+            * `None` (the default) places no limit on the number of
+              greenlets. This is useful when you want to track, but not limit,
+              greenlets. In general, a :class:`Group`
+              may be a more efficient way to achieve the same effect, but some things
+              need the additional abilities of this class (one example being the *spawn*
+              parameter of :class:`gevent.baseserver.BaseServer` and
+              its subclass :class:`gevent.pywsgi.WSGIServer`).
+
             * ``0`` creates a pool that can never have any active greenlets. Attempting
               to spawn in this pool will block forever. This is only useful
               if an application uses :meth:`wait_available` with a timeout and checks