zpaq: add page (#15024)

Co-authored-by: Wiktor Perskawiec <git@spageektti.cc>
Co-authored-by: Juri Dispan <juri.dispan@posteo.net>

pages/common/zpaq.md

@@ -0,0 +1,28 @@
+# zpaq
+
+> Incremental journaling backup utility and archiver.
+> More information: <https://mattmahoney.net/dc/zpaq.html>.
+
+- [a]dd a file or directory to a new or existing archive:
+
+`zpaq a {{path/to/archive.zpaq}} {{path/to/file_or_directory}}`
+
+- Create or add to an encrypted archive:
+
+`zpaq a -k{{password}} {{path/to/archive.zpaq}} {{path/to/file_or_directory}}`
+
+- E[x]tract the most recent versions of files:
+
+`zpaq x {{path/to/archive.zpaq}}`
+
+- [l]ist the archive contents:
+
+`zpaq l {{path/to/archive.zpaq}}`
+
+- Set the level of compression (higher means more compression but slower):
+
+`zpaq a {{path/to/archive.zpaq}} -m{{1|2|3|4|5}} {{path/to/file_or_directory}}`
+
+- E[x]tract the specified files from the archive that are not newer than the specified date:
+
+`zpaq x {{path/to/archive.zpaq}} {{path/in/archive/to/extract}} -to {{path/to/output}} -until {{YYYY-MM-DD}}`