add Go version information to README
diff --git a/README.md b/README.md
index 96582c3..aab2a96 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,12 @@
We strictly follow [semantic versioning](https://semver.org).
+## Go compatibility
+
+This library is built in Go, and uses the [support policy](https://golang.org/doc/devel/release.html#policy) of Go as its support policy. The two latest major releases of Go are supported by terraform-exec.
+
+Currently, that means Go **1.16** or later must be used.
+
## Usage
The `Terraform` struct must be initialised with `NewTerraform(workingDir, execPath)`.
