Update 'go install' instructions

Author: markdingo

README.md

@@ -64,12 +64,17 @@ to install the executable and manpage in `/usr/local`.
 
 ### `go install`
 
+```bash
+go install github.com/markdingo/fad@latest
+```
+for the latest official release, or if you're after the leading edge:
+
 ```bash
 go install github.com/markdingo/fad@main
 ```
 
 `go install` performs all the downloading, building and installing with the executable
-ending up in either `$GOPATH/bin`, `$HOME/go/bin` or $GOBIN depending on your setup.
+ending up in either `$GOPATH/bin`, `$HOME/go/bin` or `$GOBIN` depending on your setup.
 
 ### `make install`