Documentation update

[Ross Mohn]

LilyPond Usage Manual v2.20.0 Section 4.4.2 OpenOffice and LibreOffice 
<http://lilypond.org/doc/v2.20/Documentation/usage/openoffice-and-libreoffice>, 
please update the link when clicking on OOoLilyPond from the old 
http://ooolilypond.sourceforge.net/ to the new 
https://github.com/openlilylib/LO-ly. Also, replace this text:

----
Although this is no longer being developed, it appears to still work 
with version 4.
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with this:

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OOoLilyPond (OLy) works with recent versions of LibreOffice and 
OpenOffice. Older versions should work as well. It has even been tested 
with OpenOffice 2.4 without issues.
----

Thanks! -Ross

--
Ross Mohn <address@hidden>
OpenPGP: 0xFBB698141F0A6737
http://waxandwane.org/