Use the same changes file for bug7191 as in 0.2.[23]

changes/bug7191

- o Bugfixes
-   - The smartlist_bsearch_idx() function was broken for lists of length zero
-     or one; fix it.  This fixes bug7191.
+  o Major bugfixes:
+    - Fix a denial of service attack by which any directory authority
+      could crash all the others, or by which a single v2 directory
+      authority could crash everybody downloading v2 directory
+      information. Fixes bug 7191; bugfix on 0.2.0.10-alpha.