fix spacing

Doc/library/development.rst

@@ -9,7 +9,7 @@ The modules described in this chapter help you write software.  For example, the
 :mod:`pydoc` module takes a module and generates documentation based on the
 module's contents.  The :mod:`doctest` and :mod:`unittest` modules contains
 frameworks for writing unit tests that automatically exercise code and verify
-that the expected output  is produced.
+that the expected output is produced.
 
 The list of modules described in this chapter is: