unshare: add page (#7920)

pages/linux/unshare.md

@@ -0,0 +1,12 @@
+# unshare
+
+> Execute a command in new user-defined namespaces.
+> More information: <https://www.kernel.org/doc/html/latest/userspace-api/unshare.html>.
+
+- Execute a command without sharing access to connected networks:
+
+`unshare --net {{command}} {{command_arguments}}`
+
+- Execute a command as a child process without sharing mounts, processes, or networks:
+
+`unshare --mount --pid --net --fork {{command}} {{command_arguments}}`