Remove erroneous section heading "ExitPolicyDefault"

The anchor here was originally introduced to make sure that the
manpage would format correctly, but we had mistaken it for a section
anchor, and introduced a bogus section heading in 3563a2c8194ebe94.

Fixes bug 25582; bugfix on 0.3.3.1-alpha.

changes/bug25582

@@ -0,0 +1,3 @@
+  o Minor bugfixes (documentation):
+    - Revert a misformatting issue in the ExitPolicy
+      documentation. Fixes bug 25582; bugfix on 0.3.3.1-alpha.

doc/tor.1.txt

@@ -1904,7 +1904,7 @@ is non-zero):
        reject *:6881-6999
        accept *:*
 
-[[ExitPolicyDefault]] **ExitPolicyDefault**::
+[[ExitPolicyDefault]]::
     Since the default exit policy uses accept/reject *, it applies to both
     IPv4 and IPv6 addresses.