Update ReleaseNotes for acer/iopt=7 fix.

ReleaseNotes.md

@@ -4,6 +4,7 @@ Given here are some release notes for NJOY2016. Each release is made through a f
 ## [NJOY2016.72](https://github.com/njoy/NJOY2016/pull/xxx)
 This update fixes the following issues:
   - Fixed an issue in GROUPR related to an error coming up in production matrix calculations. Depending on when a user asks for a production matrix associated to a reaction, it is possible that the reference frame of the previous reaction is used instead (caused by erronously defining an already declared global variable as local with a "save" attribute). In some circumstances, this causes NJOY2016 to error out (with a message related to unsupported reference frames). No test results had to be updated due to this change.
+  - Fixed issues in acer to properly print already existing dosimetry and photoatomic ace files when running a stand-alone acer iopt=7 job.
 
 ## [NJOY2016.71](https://github.com/njoy/NJOY2016/pull/301)
 This update adds the new MF7 MT451 (thermal scattering general information) ENDF format to MODER so that this module will be able to interpret the new MF7 section. No other capability in NJOY2016 currently uses the information in this section.