Update link

Fixes ufs-community#643.

docs/source/chgres_cube.rst

@@ -236,7 +236,7 @@ The following four sets of files/directories should all be located in the same d
 	      * CRES.vegetation_greenness.tile7.halo4.nc (vegetation greenness)
 	      * CRES.vegetation_type.tile7.halo4.nc (vegetation type)
 
-      * FV3 vertical coordinate file.  Text file. Located here `./fix_am <https://ftp.emc.ncep.noaa.gov/EIB/UFS/global/fix/fix_am.v20191213>`_.
+      * FV3 vertical coordinate file.  Text file.  `Located here <https://noaa-ufs-srw-pds.s3.amazonaws.com/index.html#fix/fix_am/>`_.
 	      * global_hyblev.l$LEVS.txt
 
       * Input data files. GRIB2 only.  See the next section for how to find this data.