[I18N] *: export source terms

And add administration.pot

Author: mart-e

.tx/config

@@ -2,6 +2,11 @@
 host = https://www.transifex.com
 type = PO
 
+[odoo-15-doc.administration]
+file_filter = locale/<lang>/LC_MESSAGES/administration.po
+source_file = locale/sources/administration.pot
+source_lang = en
+
 [odoo-15-doc.applications]
 file_filter = locale/<lang>/LC_MESSAGES/applications.po
 source_file = locale/sources/applications.pot