Doc: Usage - Update section on articulate.ly

Issue 4534

The section on MIDI w/articulate.ly
was out of date. This section
has been updated accordingly,
including an @ref to the
Notation Reference where
it is more fully explained.

Updated the intro para to this section
and includes some useful @refs.

[pkx166h, 2015-08-02 10:06:35]

Updated intro para to this section and added some @refs

[Trevor Daniels, 2015-08-02 19:50:42]

https://codereview.appspot.com/259130043/diff/20001/Documentation/usage/exter...
File Documentation/usage/external.itely (right):

https://codereview.appspot.com/259130043/diff/20001/Documentation/usage/exter...
Documentation/usage/external.itely:780: @rweb{Easier editing} and @ruser{Working
with input files}.
I think what we want to say here is that some users have produced files that can
be @code{\include}d in LilyPond to produce certain effects, and the ones that
are listed below are part of the LilyPond distribution.

https://codereview.appspot.com/259130043/diff/20001/Documentation/usage/exter...
Documentation/usage/external.itely:797: slurs) according toe the articulation
markings attached to them; for
toe->to

[pkx166h, 2015-08-03 07:03:27]

With Trevor's suggestions and adjustments.

[pkx166h, 2015-08-03 07:05:28]

With Trevor's suggestions and adjustments.

[pkx166h, 2015-08-03 07:06:27]

Thanks Trevor

I removed the last para as it was redundant. Simplified the explanatory para for
Articulate and added an @ruser{} ref to the MIDI section.

https://codereview.appspot.com/259130043/diff/20001/Documentation/usage/exter...
File Documentation/usage/external.itely (right):

https://codereview.appspot.com/259130043/diff/20001/Documentation/usage/exter...
Documentation/usage/external.itely:780: @rweb{Easier editing} and @ruser{Working
with input files}.
On 2015/08/02 19:50:42, Trevor Daniels wrote:
> I think what we want to say here is that some users have produced files that
can
> be @code{\include}d in LilyPond to produce certain effects, and the ones that
> are listed below are part of the LilyPond distribution.

Done.

https://codereview.appspot.com/259130043/diff/20001/Documentation/usage/exter...
Documentation/usage/external.itely:797: slurs) according toe the articulation
markings attached to them; for
On 2015/08/02 19:50:42, Trevor Daniels wrote:
> toe->to

Done.

[pkx166h, 2015-08-08 05:22:08]

author	James Lowe <pkx166h@gmail.com>	
	Mon, 3 Aug 2015 15:40:24 +0000 (16:40 +0100)
committer	James Lowe <pkx166h@gmail.com>	
	Sat, 8 Aug 2015 05:10:54 +0000 (06:10 +0100)
commit	0cdc6bf50fb78281d7a0e6a339514b87e8d9dec3