DOC: Make API reference section concise

revise the typo "in not guaranteed" to "is not guaranteed"

Author: Wilson

doc/source/api.rst

@@ -6,19 +6,18 @@ API Reference
 *************
 
 This page gives an overview of all public pandas objects, functions and
-methods. In general, all classes and functions exposed in the top-level
-``pandas.*`` namespace are regarded as public.
+methods. All classes and functions exposed in ``pandas.*`` namespace are public.
 
-Further some of the subpackages are public, including ``pandas.errors``,
-``pandas.plotting``, and ``pandas.testing``. Certain functions in the
-``pandas.io`` and ``pandas.tseries`` submodules are public as well (those
-mentioned in the documentation). Further, the ``pandas.api.types`` subpackage
-holds some public functions related to data types in pandas.
+Some subpackages are public which include :module:`pandas.errors`,
+:module:`pandas.plotting`, and :module:`pandas.testing`. Public functions in
+:module:`pandas.io` and :module:`pandas.tseries` submodules are mentioned in
+the documentation. :module:`pandas.api.types` subpackage holds some
+public functions related to data types in pandas.
 
 
 .. warning::
 
-    The ``pandas.core``, ``pandas.compat``, and ``pandas.util`` top-level modules are considered to be PRIVATE. Stability of functionality in those modules in not guaranteed.
+    The :module:`pandas.core`, :module:`pandas.compat`, and :module:`pandas.util` top-level modules are PRIVATE. Stable functionality in such modules is not guaranteed.
 
 
 .. _api.functions: