Fix some spelling mistakes found by Ezio.

pep-0399.txt

@@ -132,13 +132,13 @@ a class being a ``type`` when implemented in C. The semantics
 equivalence requirement also dictates that no public API be provided
 in accelerated code that does not exist in the pure Python code.
 Without this requirement people could accidentally come to rely on a
-detail in the acclerated code which is not made available to other VMs
+detail in the accelerated code which is not made available to other VMs
 that use the pure Python implementation. To help verify that the
 contract of semantic equivalence is being met, a module must be tested
 both with and without its accelerated code as thoroughly as possible.
 
 As an example, to write tests which exercise both the pure Python and
-C acclerated versions of a module, a basic idiom can be followed::
+C accelerated versions of a module, a basic idiom can be followed::
 
     import collections.abc
     from test.support import import_fresh_module, run_unittest
@@ -168,7 +168,7 @@ C acclerated versions of a module, a basic idiom can be followed::
 
     class AcceleratedExampleTest(ExampleTest):
 
-        """Test using the acclerated code."""
+        """Test using the accelerated code."""
 
         heapq = c_heapq