feat(supported-version): validate custom_versions

Previously, @danslo reported that he tried to use `custom_versions` without
setting the kind. This isn't the correct behavior.
I've added a validator to alert him of this.

supported-version/src/kind/kinds.ts

@@ -0,0 +1,12 @@
+/**
+ * Acceptable arguments for version `kind`
+ */
+export const KNOWN_KINDS = {
+    'currently-supported': true,
+    'latest': true,
+    'custom': true,
+    'nightly': true,
+    'all': true,
+}
+
+export type Kind = keyof typeof KNOWN_KINDS;