Fix a few markup/grammar nits

Doc/library/abc.rst

@@ -126,7 +126,7 @@ This module provides the following class:
 
 It also provides the following decorators:
 
-.. decorator:: abstractmethod(function)
+.. decorator:: abstractmethod
 
    A decorator indicating abstract methods.
 
@@ -161,7 +161,7 @@ It also provides the following decorators:
       multiple-inheritance.
 
 
-.. decorator:: abstractclassmethod(function)
+.. decorator:: abstractclassmethod
 
    A subclass of the built-in :func:`classmethod`, indicating an abstract
    classmethod. Otherwise it is similar to :func:`abstractmethod`.
@@ -176,7 +176,7 @@ It also provides the following decorators:
    .. versionadded:: 3.2
 
 
-.. decorator:: abstractstaticmethod(function)
+.. decorator:: abstractstaticmethod
 
    A subclass of the built-in :func:`staticmethod`, indicating an abstract
    staticmethod. Otherwise it is similar to :func:`abstractmethod`.

Doc/library/io.rst

@@ -236,7 +236,7 @@ I/O Base Classes
    Note that calling any method (even inquiries) on a closed stream is
    undefined.  Implementations may raise :exc:`IOError` in this case.
 
-   IOBase (and its subclasses) support the iterator protocol, meaning that an
+   IOBase (and its subclasses) supports the iterator protocol, meaning that an
    :class:`IOBase` object can be iterated over yielding the lines in a stream.
    Lines are defined slightly differently depending on whether the stream is
    a binary stream (yielding bytes), or a text stream (yielding character

Doc/library/sys.rst

@@ -739,7 +739,7 @@ always available.
    For other systems, the values are:
 
    ====================== ===========================
-   System                 :data:`platform` value
+   System                 ``platform`` value
    ====================== ===========================
    Linux (2.x *and* 3.x)  ``'linux2'``
    Windows                ``'win32'``