xxhsum: add page (#8947)

pages/linux/xxhsum.md

@@ -0,0 +1,12 @@
+# xxhsum
+
+> Print or verify checksums using fast non-cryptographic algorithm xxHash.
+> More information: <https://github.com/Cyan4973/xxHash>.
+
+- Calculate the checksum for a file using a specific algorithm:
+
+`xxhsum -H{{0|32|64|128}} {{path/to/file}}`
+
+- Run benchmark:
+
+`xxhsum -b`