HPCC-8956 Add documentation for #option ('divideByZero')

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #4257 from ghalliday/issue8956

HPCC-8956 Add documentation for #option ('divideByZero')

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>