doc: timer -> time-tracker-4-browser

Author: sheepzh

doc/safari-install.md

@@ -7,7 +7,7 @@ So please install it **manually**, GG Safari.
 
 ```shell
 git clone https://github.com/sheepzh/time-tracker-4-browser.git
-cd timer
+cd time-tracker-4-browser
 ```
 
 ## 1. Install tools