fix(readme): update installation

i remembered cargo will install from a git repo

README.md

@@ -1,4 +1,5 @@
 # define
+
 a small, simple tool to define words from the terminal.
 
 definitions are from the [free dictionary api](https://freedictionaryapi.com/).
@@ -26,7 +27,11 @@ Options:
 
 ## installation
 
-there is currently no automated installation. simply build the program and place the resulting executable in your path.
+install using cargo.
+
+```
+cargo install cargo install --git https://git.ozzy.top/ozzy/define
+```
 
 ## building