Updated README.md.

README.md

@@ -7,3 +7,13 @@ Show current net speed on panel.
 This extension is inspired by <https://github.com/biji/simplenetspeed/> which has some annoying flickers existing for a long time so I decide to create my own alternative. I removed all features that I won't use.
 
 It only shows text like `↓ 777 K/s ↑ 2.33 K/s` on the right part of panel. No font size changing, no total downloaded bytes, no bits.
+
+# Usage
+
+```
+$ git clone https://github.com/AlynxZhou/gnome-shell-extension-net-speed.git ~/.local/share/gnome-shell/extensions/[email protected]
+```
+
+or install it from <https://extensions.gnome.org/extension/4478/net-speed/>.
+
+Then restart GNOME Shell and enable Net Speed from GNOME Extensions.