Update Purchase Limit of employee via CSV Import

1. Prepare a CSV File with the following headers:
Internal ID (internal ID of the Employee record)
Purchase Limit

2. Import the file:
- Navigate to Setup> Import/Export> Import CSV Records
- Import type  = Employees
- Record type = Employees
- Click Select and upload the CSV File from step 1
- Click Next
- Data Handling = Update
- Map the Fields
                        Internal ID ↔ Internal ID
                        Purchase Limit ↔ Purchase Limit
- Assign an Import Map name and hit Save & Run