Insert link to an actual catalog

TODO in astroquery/docs/astrometry_net/astrometry_net.rst (54)

```
Solving from a list of sources

==============================

The most efficient way to use `astrometry.net`_ is to pass it a list of
sources in an image instead of uploading the entire image. The data can be in
an `astropy.table.Table`, pandas data frame or something other structure.

The only important requirement is that **the list must be sorted by flux in
descending order**.

In the example below, assume that ``catalog.fits`` is a table of pixel positions
(columns ``X_IMAGE`` and ``Y_IMAGE``) and flux (column ``FLUX``) and perhaps
other columns, and that the image is 3073 by 2048 pixels.

The ``solve_timeout`` used below is the time, in seconds, to allow the
`astrometry.net`_ server to find a solution. It typically makes sense for this
to be a longer time than the timeout set in
`astroquery.astrometry_net.AstrometryNetClass.TIMEOUT`, which is intended to
act primarily as a timeout for network transactions.

TODO: Insert link to an actual catalog

.. code-block:: python

from astropy.table import Table
from astroquery.astrometry_net import AstrometryNet
``
```

Open astroquery/docs/astrometry_net/astrometry_net.rst around line 54 and read the “Solving from a list of sources” example. Replace the TODO with a link to an actual catalog relevant to the example, then build or preview the documentation to confirm the link and formatting work.

Written by the indexing model from the issue text.