minor: Fix incorrect traceExceptions example

The current example generates an error. A bool is expected.

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1492 count, create, shardCollection

Signed-off-by: Sam Kleinman <samk@10gen.com>
minor: edits
DOCS-1492 edits
Update 2.4-upgrade.txt

Signed-off-by: Sam Kleinman <samk@10gen.com>