changes.tely: deal with \transposition and instrumentTransposition changes

Documentation/changes.tely

Index: Documentation/changes.tely
diff --git a/Documentation/changes.tely b/Documentation/changes.tely
index d3eb33d83b09a258b0ede114ae0ded72b4034eef..dab40a311297339e0686d820f7704877dd16d10d 100644
--- a/Documentation/changes.tely
+++ b/Documentation/changes.tely
@@ -62,6 +62,29 @@ which scares away people.
 @end ignore
 
 @item
+The meaning of @code{instrumentTransposition} has been reversed.
+After
+@example
+\set instrumentTransposition = #@{ b #@}
+@end example
+a written @code{c'} now sounds like @code{b}.  Previously, this
+would have been the other way round.  This and the following change

[Keith, 2013/02/27 05:58:58]

Maybe "With the related change to @code{\transpose}, this makes dealing with
..."
But I would guess people will understand 'following' to mean following in
reading order, as you intended.

+should make dealing with transposing instruments more
+straightforward.
+
+@item
+The music generated by @code{\set} and @code{\override} commands
+is no longer affected by @code{\transpose}.  The main consequence
+is that @code{\transpose} will transpose audible/@/concert pitch and
+printed pitch by the same amount even when the transposed music
+contains @code{\transposition}.  Previously,
+@example
+\transpose c' f' \transposition bes'
+@end example
+was equivalent to @code{\transposition f'}.  Now it stays

[Keith, 2013/02/27 05:58:58]

(and @code{\whateverItWasCalled f'} is available in case an old score depended
on the old behavior).

+equivalent to @code{\transposition bes'}.
+
+@item
 Tuplets are now created with the @code{\tuplet} command, which
 takes a fraction @code{@var{t}/@var{n}} to specify that @var{t}
 notes are played in the time usually allowed for @var{n}. One