REMINDER: Software string freeze is 30 July

[Ben Cotton]

The software string freeze begins 30 July. For more information, see
the String Freeze Policy[1]. For more upcoming development[2] and
translation[3] milestones, see the schedule site.

[1] https://fedoraproject.org/wiki/Software_String_Freeze_Policy
[2] https://fedorapeople.org/groups/schedule/f-31/f-31-devel-tasks.html
[3] https://fedorapeople.org/groups/schedule/f-31/f-31-trans-tasks.html