os: trivial comment fix

"Geese" here looks like an autocorrect-o of "oses", I think writing it out
makes more sense.

Change-Id: Iba89a6c0b94657e2e93937cc153f07aea1d04e04
GitHub-Last-Rev: 4f3a780f327d6c807e9b154d781ee69a10d391e4
GitHub-Pull-Request: golang/go#74332
Reviewed-on: https://go-review.googlesource.com/c/go/+/682776
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

src/os/file.go

@@ -616,7 +616,7 @@ func UserHomeDir() (string, error) {
 	if v := Getenv(env); v != "" {
 		return v, nil
 	}
-	// On some geese the home directory is not always defined.
+	// On some operating systems the home directory is not always defined.
 	switch runtime.GOOS {
 	case "android":
 		return "/sdcard", nil