add zstd to docs, completion

Signed-off-by: Zen <[email protected]>

Author: desultory

completion/_pycpio

@@ -24,8 +24,8 @@ args=("-i[input archive]:archive:_files"
       "--set-group[GID]:GID:_groups"
       "-m[file mode]:mode"
       "--set-mode[file modes]:mode"
-      "-z[compression]:compression:(xz)"
-      "--compress[compression]:compression:(xz)"
+      "-z[compression]:compression:(xz zstd)"
+      "--compress[compression]:compression:(xz zstd)"
       "-o[output archive]:archive:_files"
       "--output[output archive]:archive:_files"
       "--log-file[specify the log file]:log file:_files"

readme.md

@@ -6,7 +6,9 @@
 
 A library for creating CPIO files in Python.
 
-Currently, the library only supports the New ASCII format, and xz compression
+Currently, the library only supports the New ASCII format.
+
+xz compression and zstd compression types are suppored.
 
 This library is primary designed for use in [ugrd](https://github.com/desultory/ugrd) to create CPIO archives for use in initramfs.