chore: add instructions to install gitmux

README.md

@@ -43,3 +43,18 @@ cp *.otf ~/.local/share/fonts
 ```
 
 2. use as terminal font via preferences
+
+## install `gitmux` for git info on tmux bar
+1. Download the latest [release](https://github.com/arl/gitmux/releases)
+2. Extract to local shared and link
+
+```bash
+cd Downloads
+tar -C ~/.local/share/ -xzf ./gitmux...tar.gz
+
+# link binary
+ln -s ~/.local/share/gitmux ~/.local/bin/gitmux
+
+# confirm
+gitmux -V
+```