Document FermiLATClass

TODO in astroquery/fermi/core.py (20)
```
@async_to_sync
class FermiLATClass(BaseQuery):
"""
TODO: document
"""

request_url = conf.url
result_url_re = re.compile('The results of your query may be found at '
'

Start in astroquery/fermi/core.py at FermiLATClass and read the surrounding Fermi module to understand the class's purpose and query interface. Document the class in its existing docstring, covering what it accesses and how it is used; done means the TODO is replaced with useful, accurate documentation.

Written by the indexing model from the issue text.