text: Title: Unnamed Series visualization add axis name
  Body: In cases where the column does not have a name, such as in a Series visualization, we should add an axis label when the `name` property of the Series is not present. In this example, we can replace `(binned)` with `Series (binned)`. Need to check other edge cases where the axis name might be empty.
  ```python
  df = pd.read_csv("https://raw.githubusercontent.com/lux-org/lux-datasets/master/data/employee.csv")
  df["YearsAtCompany"]/df["TotalWorkingYears"]
  ```
  ![image](https://user-images.githubusercontent.com/5554675/105575016-3c70a600-5da3-11eb-80da-ff367f154803.png)
  