xdelta: add page (#6313)

pages/common/xdelta.md

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+# xdelta
+
+> Delta encoding utility.
+> Often used for applying patches to binary files.
+> More information: <http://xdelta.org>.
+
+- Apply a patch:
+
+`xdelta -d -s {{path/to/input_file}} {{path/to/delta_file.xdelta}} {{path/to/output_file}}`
+
+- Create a patch:
+
+`xdelta -e -s {{path/to/old_file}} {{path/to/new_file}} {{path/to/output_file.xdelta}}`