cjxl, djxl: move to common (#13621)

pages/common/cjxl.md

@@ -0,0 +1,17 @@
+# cjxl
+
+> Compress images to JPEG XL.
+> Accepted input extensions are PNG, APNG, GIF, JPEG, EXR, PPM, PFM, PAM, PGX, and JXL.
+> More information: <https://github.com/libjxl/libjxl>.
+
+- Convert an image to JPEG XL:
+
+`cjxl {{path/to/image.ext}} {{path/to/output.jxl}}`
+
+- Set quality to lossless and maximize compression of the resulting image:
+
+`cjxl --distance 0 --effort 9 {{path/to/image.ext}} {{path/to/output.jxl}}`
+
+- Display an extremely detailed help page:
+
+`cjxl --help --verbose --verbose --verbose --verbose`