powertop: add page (#3882)

Co-authored-by: Zlatan Vasović <zlatanvasovic@gmail.com>

pages/linux/powertop.md

@@ -0,0 +1,15 @@
+# powertop
+
+> Optimize battery power usage.
+
+- Calibrate power usage measurements:
+
+`sudo powertop --calibrate`
+
+- Generate HTML power usage report in the current directory:
+
+`sudo powertop --html={{power_report.html}}`
+
+- Tune to optimal settings:
+
+`sudo powertop --auto-tune`