liquidctl: add page (#10664)

Co-authored-by: Lena <126529524+acuteenvy@users.noreply.github.com>

pages/common/liquidctl.md

@@ -0,0 +1,20 @@
+# liquidctl
+
+> Control liquid coolers.
+> More information: <https://github.com/liquidctl/liquidctl>.
+
+- List available devices:
+
+`liquidctl list`
+
+- Initialize all supported devices:
+
+`sudo liquidctl initialize all`
+
+- Print the status of available liquid coolers:
+
+`liquidctl status`
+
+- Match a string in product name to pick a device and set its fan speed to 0% at 20°C, 50% at 50°C and 100% at 70°C:
+
+`liquidctl --match {{string}} set fan speed {{20 0 50 50 70 100}}`