chore: removed duplicate null assignment and took out an assignment to o...

More cleanup of the docs within the code.

I also discovered that [offset](https://github.com/jtymes/ux-angularjs-datagrid/compare/webux:0e35566...jtymes:b066251#diff-6c2fcd85c8e23fcc1b15ee3d86a99618L828) was being set here and then a few lines later being re-set without using the initial value. It was also using a magic number, not `options.rowHeight`. 

The other change was just [here](https://github.com/jtymes/ux-angularjs-datagrid/compare/webux:0e35566...jtymes:b066251#diff-6c2fcd85c8e23fcc1b15ee3d86a99618L1400) where `values = null` is being called twice.