pkgctl-diff: add page (#10599)

pages/linux/pkgctl-diff.md

@@ -0,0 +1,21 @@
+# pkgctl diff
+
+> Compare package files using different modes.
+> See also: `pkgctl`.
+> More information: <https://man.archlinux.org/man/pkgctl-diff.1>.
+
+- Compare package files in tar content [l]ist different mode (default):
+
+`pkgctl diff --list {{path/to/file|pkgname}}`
+
+- Compare package files in [d]iffoscope different mode:
+
+`pkgctl diff --diffoscope {{path/to/file|pkgname}}`
+
+- Compare package files in `.PKGINFO` different mode:
+
+`pkgctl diff --pkginfo {{path/to/file|pkgname}}`
+
+- Compare package files in `.BUILDINFO` different mode:
+
+`pkgctl diff --buildinfo {{path/to/file|pkgname}}`