Python, doc: References to section on API graphs.

Author: yoff

docs/codeql/codeql-language-guides/analyzing-data-flow-in-python.rst

@@ -99,6 +99,8 @@ Python has builtin functionality for reading and writing files, such as the func
 
 ➤ `See this in the query console on LGTM.com <https://lgtm.com/query/8635258505893505141/>`__. Two of the demo projects make use of this low-level API.
 
+Notice the use of the ``API`` module for referring to library functions. It is further described in ":doc:`Using API graphs in Python <using-api-graphs-in-python>`."
+
 Unfortunately this will only give the expression in the argument, not the values which could be passed to it. So we use local data flow to find all expressions that flow into the argument:
 
 .. code-block:: ql

docs/codeql/codeql-language-guides/codeql-for-python.rst

@@ -21,6 +21,8 @@ Experiment and learn how to write effective and efficient queries for CodeQL dat
 
 -  :doc:`Analyzing data flow in Python <analyzing-data-flow-in-python>`: You can use CodeQL to track the flow of data through a Python program to places where the data is used.
 
+-  :doc:`Using API graphs in Python <using-api-graphs-in-python>`: API graphs are a uniform interface for referring to functions, classes, and methods defined in external libraries.
+
 -  :doc:`Functions in Python <functions-in-python>`: You can use syntactic classes from the standard CodeQL library to find Python functions and identify calls to them.
 
 -  :doc:`Expressions and statements in Python <expressions-and-statements-in-python>`: You can use syntactic classes from the CodeQL library to explore how Python expressions and statements are used in a codebase.

docs/codeql/codeql-language-guides/codeql-library-for-python.rst

@@ -23,10 +23,7 @@ The CodeQL library for Python incorporates a large number of classes. Each class
 -  **Data flow** - classes that represent entities from the data flow graphs.
 -  **API graphs** - classes that represent entities from the API graphs.
 
-The first two categories are described below. See ":doc:`Analyzing data flow in Python <analyzing-data-flow-in-python>`" for a description of data flow and associated classes.
-
-..
-   and [TO COME IN FUTURE PR] for a description of API graphs and their use.
+The first two categories are described below. See ":doc:`Analyzing data flow in Python <analyzing-data-flow-in-python>`" for a description of data flow and associated classes and ":doc:`Using API graphs in Python <using-api-graphs-in-python>`" for a description of API graphs and their use.
 
 Syntactic classes
 -----------------