Improve explanation of required based on feedback

docs/Gopkg.toml.md

@@ -21,7 +21,14 @@ cd vendor/pkg/to/install
 go install .
 ```
 
-Another option is to use [virtualgo](https://github.com/GetStream/vg), which installs dependencies in the `required` list automatically.
+This only works reliably if this is the only project to install these executables. This is not enough if you want to be able to run a different version of the same executable depending on the project you're working. In that case you have to use a different `GOBIN` for each project, by doing something like this before running the above commands:
+
+```bash
+export GOBIN=$PWD/bin
+export PATH=$GOBIN:$PATH
+```
+
+You might also try [virtualgo](https://github.com/GetStream/vg), which installs dependencies in the `required` list automatically in a project specific `GOBIN`.
 
 ## `ignored`
 `ignored` lists a set of packages (not projects) that are ignored when dep statically analyzes source code. Ignored packages can be in this project, or in a dependency.