Change formatting of units in XSD documentation

[macintoshpie]

• make sure all elements that are unit specific include a unit specification at the end of the documentation.
• replace "(unit)" with "[unit]"
• test bsyncpy

[macintoshpie]

Just a thought, but if our goal is for applications to parse units, we should instead use xs:appinfo or specify reusable types for use with elements that have units. If our goal is aesthetics then changing the documentation text alone is good.