[MathML3-LC] Grammar fix for elementary math

This is in response to a last call comment that there were some grammatical
problems with the bulleted list of elements for elementary math layouts.
The new wording can be seen at:

http://monet.nag.co.uk/~dpc/draft-spec/chapter<http://monet.nag.co.uk/%7Edpc/draft-spec/chapter3-d.html#presm.elementary>
3-d.html#presm.elementary<http://www.w3.org/Math/Group/draft-spec/chapter3-d.html#presm.elementary>


Neil Soiffer
Senior Scientist
Design Science, Inc.
www.dessci.com
~ Makers of MathType, MathFlow, MathPlayer, MathDaisy, Equation Editor ~

<http://monet.nag.co.uk/%7Edpc/draft-spec/chapter6-d.html#world-int-combine-other>