xxd: add page (#1424)

pages/common/xxd.md

@@ -0,0 +1,23 @@
+# xxd
+
+> Create a hexdump from a binary file or vice-versa.
+
+- Generate a hexdump from a binary file and display the output to console:
+
+`xxd {{input_file}}`
+
+- Send the hexdump output to a file:
+
+`xxd {{input_file}} {{output_file}}`
+
+- Format output in columns of 8 octets per line:
+
+`xxd -c {{8}} {{input_file}}`
+
+- Display in plain hex format without any gaps:
+
+`xxd -p {{input_file}}`
+
+- Revert a plaintext hex into binary and store it in an output file:
+
+`xxd -r -p {{input_file}} {{output_file}}`