#11726: Make linecache docs reflect that all files are treated the same.

Being able to read non-python text files is not a purpose of linecache, but it
does work and people use it.  This changeset adjusts the language to make it
clear that Python files are not treated uniquely, but does not go so far as to
say reading non-python files is explicitly supported.

Doc/library/linecache.rst

@@ -14,9 +14,9 @@ attempting to optimize internally, using a cache, the common case where many
 lines are read from a single file.  This is used by the :mod:`traceback` module
 to retrieve source lines for inclusion in  the formatted traceback.
 
-The :func:`tokenize.open` function is used to open Python source files. This
+The :func:`tokenize.open` function is used to open files. This
 function uses :func:`tokenize.detect_encoding` to get the encoding of the
-Python source file.
+file; in the absence of an encoding token, the file encoding defaults to UTF-8.
 
 The :mod:`linecache` module defines the following functions: