swapoff: add page (#2003)

pages/linux/swapoff.md

@@ -0,0 +1,19 @@
+# swapoff
+
+> Disables device or file for swapping.
+
+- Disable a given swap partition:
+
+`swapoff {{/dev/sdb7}}`
+
+- Disable a given swap file:
+
+`swapoff {{path/to/file}}`
+
+- Disable all swap areas:
+
+`swapoff -a`
+
+- Disable swap by label of a device or file:
+
+`swapoff -L {{swap1}}`