README: fix wording for Go version and OS support
Also drop link to appveyor since it lags travis and travis already shows
the versions we support.
@@ -10,7 +10,7 @@ go get -u gonum.org/v1/gonum/...
## Supported Go versions
-Gonum supports and tests on the two most recent minor versions of Go on [Linux](https://github.com/gonum/gonum/blob/master/.travis.yml#L6-L11) and [Windows](https://github.com/gonum/gonum/blob/master/appveyor.yml#L13-L18).
+Gonum supports and tests on the [two most recent Go releases](https://github.com/gonum/gonum/blob/master/.travis.yml#L6-L10) on Linux, macOS and Windows.
## Build tags
