docs: add note about the column names fix

Co-authored-by: keflavich <adam.g.ginsburg@gmail.com>

docs/vizier/vizier.rst

@@ -14,6 +14,15 @@ radius. Similar to the VizieR web interface, the queries may be further
 constrained by specifying a choice of catalogs, keywords as well as filters on
 individual columns before retrieving the results.
 
+.. note::
+    In astroquery>=0.4.8 an issue where the column names received from this module did
+    not correspond to the columns of the online catalogs was solved.
+    Namely, columns with special characters like ``r'mag`` were renamed into ``r_mag``
+    and columns starting with a number like ``2MASS`` were prepended with an underscore
+    ``_2MASS``.
+    Now that this is fixed, the column names are the same in VizieR's webpages and in
+    the tables received (for the two examples: you'll see ``r'mag`` and ``2MASS``). 
+
 Table Discover
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