update upgrade instructions to more clearly describe 'go get -u foo'
diff --git a/Modules.md b/Modules.md
index 9432014..035434b 100644
--- a/Modules.md
+++ b/Modules.md
@@ -336,7 +336,9 @@
To upgrade or downgrade to a more specific version, 'go get' allows version selection to be overridden by adding an @version suffix or ["module query"](https://golang.org/cmd/go/#hdr-Module_queries) to the package argument, such as `go get foo@v1.6.2`, `go get foo@e3702bed2`, or `go get foo@'<v1.6.2'`.
-`go get foo` updates to the latest version with a [semver](https://semver.org/) tag. (This is equivalent to `go get foo@latest` — in other words, `@latest` is the default if no `@` version is specified).
+`go get foo` updates to the latest version with a [semver](https://semver.org/) tag, or the the latest known commit if there are no semver tags ([details](https://golang.org/cmd/go/#hdr-Module_aware_go_get)). `go get foo` is equivalent to `go get foo@latest` — in other words, `@latest` is the default if no `@` version is specified.
+
+Note that a `-u` in `go get -u foo` and `go get -u foo@latest` also upgrades all the direct and indirect dependencies of `foo`. A common starting point is instead `go get foo` or `go get foo@latest` without a `-u` (and after things are working, consider `go get -u=patch foo`, `go get -u foo`, `go get -u`, or `go get -u=patch`).
Using a branch name such as `go get foo@master` is one way to obtain the latest commit regardless of whether or not it has a semver tag.
