reorganized instance section, closes #8
added acknowledgements, closes #7
barcode datatype same a string, closes #4
correction about instance nodes that can have a bind element, closes #5
spelling corrections
added area(), closes #6
added datatypes of checklist and weighted-checklist functions
added once(), closes #10
revised once(), closes #10
added that appearances can be space-separated lists, closes #12
Merge pull request #9 from opendatakit/revision-1

Revision 1