The IntervalIndex documentation makes no mention of IntervalIndex.get_loc
#### Code Sample, a copy-pastable example if possible

```python
# No code, documentation issue
```
#### Problem description

Why doesn't the documentation about IntervalIndex ([here](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.IntervalIndex.html)) contain any mention of the function [IntervalIndex.get_loc](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.IntervalIndex.get_loc.html)?

#### Expected Output

I would expect the list of class methods to include all the methods.
