This placement is better, it's not a bug fix.  ;-)  I was just in the middle of suggesting a further tweak to the wording:
```
- Astropy now uses the ERFA library instead of the IAU SOFA library for fundamental time
  transformation routines.  The ERFA library is derived, with permission, from the IAU
  SOFA library, but is distributed under a BSD license.  See the ``license/ERFA.rst`` file
  for details.
```
I think we don't need to have any judgmental words like "free" and "non-free" here, just the straight facts.  I was torn about whether to say Astropy is using ERFA for "time and coordinate" transformations, but at the moment it is really just time.  If coordinates uses ERFA by the 0.3 release then this statement can be updated at that time.