Update gaia.rst
```
>>> for column in (gaiadr1_table.get_columns()):
>>>   print(column.get_name())
```
It looks like the `get_columns()` method has been replaced with a `columns` property and `get_name()` has been replaced with `name`
So this works for me:
```
for column in table.columns:
print(column.name)
```
@@ -246,8 +246,8 @@ Once a table is loaded, columns can be inspected
>>> from astroquery.gaia import Gaia
>>> gaiadr1_table = Gaia.load_table('gaiadr1.gaia_source')
- >>> for column in (gaiadr1_table.get_columns()):
- >>> print(column.get_name())
+ >>> for column in (gaiadr1_table.columns):
+ >>> print(column.name)
solution_id
source_id
