docs: improve docs on go modules usage

www/content/build.md

@@ -110,3 +110,21 @@ Then you can run:
 ```console
 GOVERSION=$(go version) goreleaser
 ```
+
+## Go Modules
+
+ If you use Go 1.11 with go modules or vgo, when GoReleaser runs it may
+ try to download the dependencies. Since several builds run in parallel, it is
+ very likely to fail.
+
+ You can solve this by running `go mod download` before calling `goreleaser` or
+ by adding a [hook][] doing that on your `.goreleaser.yaml` file:
+
+ ```yaml
+ before:
+   hooks:
+   - go mod download
+ # rest of the file...
+ ```
+
+ [hook]: /hooks

www/content/hooks.md

@@ -17,6 +17,7 @@ before:
   hooks:
   - make clean
   - go generate ./...
+  - go mod download
 ```
 
 If any of the hooks fails the build process is aborted.