ENH: Join Absenteeism and IEQ Datasets

## User story
As a fictitious employee of MG, I want to see if there's a relationship between IEQ and employee absenteeism so that we can make a stronger case for monitoring IEQ as a part of the Total Workplace pilot.

## Acceptance criteria
In order to perform this analysis, we'll need to use the BookIt data to figure out where each employee in the absenteeism dataset sits. Naturally, a single individual will book a number of different workstations (if they're even using BookIt at all) so we'll need to use some rule-of-thumb to determine which workstation/wing we assign to them. Taking the mode of their bookings might be good. Then, once we've got a physical location for the employees in the absenteeism dataset, we can join that to the IEQ data on the physical location and date. If the dates in the datasets don't overlap, we should adjust them so that they do. If this results in a join that gives us enough data to work with, then we can request the right time periods from HR for the absenteeism/bookit datasets.

- [x] ReadMe updated with notes on where/how to access the required data.
- [ ] A single dataframe where each row is an employee with columns containing the relevant fields from the absenteeism dataset and IEQ datasets. This dataframe should include employees that weren't in the absenteeism dataset as we want to include in our sample folks that did not take leave as well.