Fixup some xrefs in docs. [skip ci]

doc/api/gevent.greenlet.rst

@@ -144,7 +144,7 @@ yet and thus would evaluate to False.
 
 .. attribute:: Greenlet.spawning_stack
 
-   A lightweight frame-like object capturing the stack when
+   A lightweight :obj:`frame <types.FrameType>`-like object capturing the stack when
    this greenlet was created as well as the stack when the spawning
    greenlet was created (if applicable). This can be passed to
    :func:`traceback.print_stack`.

doc/intro.rst

@@ -190,7 +190,7 @@ by default.
 
    A low-level event loop API is available under the
    :mod:`gevent.core` module. This module is not documented, not meant
-   for general purpose usage, and it's exact contents and semantics
+   for general purpose usage, and its exact contents and semantics
    change slightly depending on whether the libev or libuv event loop
    is being used. The callbacks supplied to the event loop API are run
    in the :class:`~gevent.hub.Hub` greenlet and thus cannot use the

doc/whatsnew_1_3.rst

@@ -44,7 +44,7 @@ gevent 1.3 supports Python 2.7, 3.4, 3.5, 3.6 and 3.7 on the CPython
    implementation.
 
 Python 3.7 is in the process of release right now and gevent is tested
-with 3.7b3.
+with 3.7b4, the last scheduled beta for Python 3.7.
 
 For ease of installation on Windows, OS X and Linux, gevent 1.3 is
 distributed as pre-compiled binary wheels, in addition to source code.
@@ -67,20 +67,22 @@ Greenlet Attributes
 attributes:
 
 - :attr:`Greenlet.spawning_greenlet` is the greenlet that created this
-  greenlet. Since the ``parent`` is usually the hub, this can be more
-  useful.
+  greenlet. Since the ``parent`` of a greenlet is almost always gevent's
+  :class:`hub <gevent.hub.Hub>`, this can be more
+  useful to understand greenlet relationships.
 - :attr:`Greenlet.spawn_tree_locals` is a dictionary of values
-  maintained through the spawn tree. This is handy to share values
-  between a set of greenlets, for example, all those involved in
-  processing a request.
-- :attr:`Greenlet.spawning_stack` is a `frame` -like object that
-  captures where the greenlet was created.
+  maintained through the spawn tree (i.e., all descendents of a
+  particular greenlet based on ``spawning_greenlet``). This is
+  convenient to share values between a set of greenlets, for example,
+  all those involved in processing a request.
+- :attr:`Greenlet.spawning_stack` is a :obj:`frame <types.FrameType>` -like object that
+  captures where the greenlet was created and can be passed to :func:`traceback.print_stack`.
 - :attr:`Greenlet.minimal_ident` is a small integer unique across all
   greenlets.
 - :attr:`Greenlet.name` is a string printed in the greenlet's repr by default.
 
 "Raw" greenlets created with `spawn_raw` default to having the
-``spawning_parent`` and ``spawn_tree_locals``.
+``spawning_greenlet`` and ``spawn_tree_locals``.
 
 This extra data is printed by the new
 :func:`gevent.util.print_run_info` function.