Typo fix for edit-tags.php

[Nao]

Here's the tiniest patch ever (?).
Just including a period into the translatable string to avoid it from showing up after the Japanese translation, where "。" is used in place of a period.

[Nao]

Include a period into i18n string

[markjaquith]

In [21216]:

Periods at the ends of sentences should be in the translated string, not outside it. Fixes an instance of that on the Tags page. props Nao. fixes #21131