[docs] Added gopath example in docs (#1957)

## Summary TSIA This was requested by community user. ## How was it tested? N/A --------- Co-authored-by: John Lago <750845+Lagoja@users.noreply.github.com>

Author: mohsenari

docs/app/docs/devbox_examples/languages/go.md

@@ -29,3 +29,30 @@ If you need additional C libraries, you can add them along with `gcc` to your pa
  "libcap"
 ]
 ```
+
+## Installing go packages that have CLIs
+
+Installing go packages in your devbox shell is as simple as `go get <package_name>` but some packages come with a CLI of their own (e.g., `godotenv`). That means after installing the package you should be able to use the CLI binary and also control where that binary is installed. This is done by setting `$GOPATH` or `$GOBIN` env variable. 
+
+With Devbox you can set these variables in the `"env"` section of your `devbox.json` file. 
+In the example below we are setting `$GOPATH` to be the same directory of our project and therefore `godotenv` binary will be located in the `bin/` subdirectory of `$GOPATH`:
+
+```json
+{
+ "packages": [
+ "go@latest"
+ ],
+ "env": {
+ "GOPATH": "$PWD",
+ "PATH": "$PATH:$PWD/bin"
+ },
+ "shell": {
+ "init_hook": [
+ "echo 'Welcome to devbox!' > /dev/null"
+ ],
+ "scripts": {}
+ }
+}
+```
+
+Running `go install github.com/joho/godotenv/cmd/godotenv@latest` will create a `bin/` subdirectory in my project and puts `godotenv` there. Since I also added that subdirectory to my `$PATH`, my devbox shell can now recognize the `godotenv` binary and I can run commands like `godotenv -h` to use `godotenv` in CLI mode.

examples/development/go/hello-world/devbox.json

@@ -2,6 +2,10 @@
  "packages": [
  "go@1.19.8"
  ],
+ "env": {
+ "GOPATH": "$HOME/go/",
+ "PATH": "$PATH:$HOME/go/bin"
+ },
  "shell": {
  "init_hook": [
  "export \"GOROOT=$(go env GOROOT)\""
@@ -10,4 +14,4 @@
  "run_test": "go run main.go"
  }
  }
-}
+}