References to publications in the docs

[Phil Holmes]

We currently refer to Gardner Read and others in the NR under the very 
sparsely populated Contemporary Music section of the NR:

http://www.lilypond.org/doc/v2.17/Documentation/notation/further-reading-and-scores-of-interest

It strikes me that this would be better at the end of section 1 of the LM:

http://www.lilypond.org/doc/v2.17/Documentation/learning/overview-of-manuals

"Further reading", plus adding at the very least Elaine Gould's book.  Does 
anyone disagree?

--
Phil Holmes