Update release notes for PRs 60 and 74

[simon-ess]

Release notes for the changes in #60 and #74 are added here. In particular, it is highlighted that #74 adds a breaking change.

[mdavidsaver]

It looks like this PR was merged while still failing CI due to the addition of an undefined variable status.

   ../save_restore.c:2095:9: error: use of undeclared identifier 'status'
          status = write_save_file(plist, NULL, NULL);
          ^
  ../save_restore.c:2096:13: error: use of undeclared identifier 'status'; did you mean 'stat'?
          if (status != 0) {
              ^~~~~~
              stat

[mdavidsaver]

Ah, wrong PR. #70 is the culprit.