chore: Translate pressbooks-multi-institution.pot in zh

76% of minimum 25% translated source file: 'pressbooks-multi-institution.pot'
on 'zh'.

Sync of partially translated files: 
untranslated content is included with an empty translation 
or source language content depending on file format

languages/pressbooks-multi-institution-zh.po

@@ -329,7 +329,7 @@ msgstr "星号 (*) 表示必填字段"
 
 #: resources/views/institutions/form.blade.php:92
 msgid "Enter exclusive email domains for this institution (e.g. utopia.edu)."
-msgstr ""
+msgstr "输入该机构的专用电子邮件域名（例如 shisu.edu.cn）。"
 
 #: resources/views/institutions/form.blade.php:153
 msgid "domain"