Extensions doc page contains errors

[rly]

Description

Bug report from the AQuA developers.

The documentation for extensions contains code that does not run.

spec = NWBDatasetSpec('A custom NWB type',
    name='qux',
    attribute=[
        NWBAttributeSpec('baz', 'a value for baz', 'text'),
    ],
    shape=(None, None)
)

The keyword attribute should be attributes. This happens more than once on the page.

The page is also outdated and should point users to the NWB Extensions Catalog and associated tools to create extensions.

[oruebel]

I would also add a link to the YouTube video of your talk ;-)