Update cheatsheets

tldr/linux/hd-idle

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+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# hd-idle
+
+> Spin down external disks after a period of idle time.
+> More information: <https://manned.org/hd-idle>.
+
+- Start a service to manage hard drive spin down. By default hard disks will spin down after 10 minutes of inactivity:
+
+`systemctl start hd-idle`
+
+- Spin down a disk immediately:
+
+`hd-idle -t {{/dev/sdX}}`
+
+- Set disks to never spin down, then set explicit idle times (in seconds) for disks which have "sda" or "sdb" in their device name:
+
+`hd-idle -i 0 -a /dev/sda -i {{300}} -a /dev/sdb -i {{1200}}`