Remove many "versionchanged" items that didn't use the official markup,
but just some text embedded in the docs.

Also remove paragraph about implicit relative imports from tutorial.
diff --git a/Doc/c-api/dict.rst b/Doc/c-api/dict.rst
index b346d68..def60d2 100644
--- a/Doc/c-api/dict.rst
+++ b/Doc/c-api/dict.rst
@@ -153,9 +153,9 @@
           ...
       }
 
-   The dictionary *p* should not be mutated during iteration.  It is safe (since
-   Python 2.1) to modify the values of the keys as you iterate over the dictionary,
-   but only so long as the set of keys does not change.  For example::
+   The dictionary *p* should not be mutated during iteration.  It is safe to
+   modify the values of the keys as you iterate over the dictionary, but only so
+   long as the set of keys does not change.  For example::
 
       PyObject *key, *value;
       Py_ssize_t pos = 0;