po4a: add page (#6493)

pages/linux/po4a-updatepo.md

@@ -0,0 +1,16 @@
+# po4a-updatepo
+
+> Update the translation (in PO format) of a documentation.
+> More information: <https://po4a.org/man/man1/po4a-updatepo.1.php>.
+
+- Update a PO file according to the modification of its origin file:
+
+`po4a-updatepo --format {{text}} --master {{path/to/master.txt}} --po {{path/to/result.po}}`
+
+- Get a list of available formats:
+
+`po4a-updatepo --help-format`
+
+- Update several PO files according to the modification of their origin file:
+
+`po4a-updatepo --format {{text}} --master {{path/to/master.txt}} --po {{path/to/po1.po}} --po {{path/to/po2.po}}`