feat: support for KV version 1 and custom-named engines (#12)

* feat: kv v1 and engine path

* doc: add custom version and engine path usage docs

Co-authored-by: Richard Simpson <richardsimpson@outlook.com>

integrationTests/e2e/e2e.test.js

@@ -3,5 +3,8 @@ describe('e2e', () => {
         expect(process.env.SECRET).toBe("SUPERSECRET");
         expect(process.env.NAMED_SECRET).toBe("SUPERSECRET");
         expect(process.env.OTHERSECRET).toBe("OTHERSUPERSECRET");
+        expect(process.env.ALTSECRET).toBe("CUSTOMSECRET");
+        expect(process.env.NAMED_ALTSECRET).toBe("CUSTOMSECRET");
+        expect(process.env.OTHERALTSECRET).toBe("OTHERCUSTOMSECRET");
     });
-});
+});