docs: update discovery tests usage (#61)

src/peer-discovery/README.md

@@ -33,19 +33,19 @@ Include this badge in your readme if you make a new module that uses interface-p
 Install `interface-discovery` as one of the dependencies of your project and as a test file. Then, using `mocha` (for JavaScript) or a test runner with compatible API, do:
 
 ```js
-const test = require('interface-discovery')
+const tests = require('libp2p-interfaces/src/peer-discovery/tests')
 
-const common = {
+describe('your discovery', () => {
-  setup () {
+  // use all of the test suits
-    return YourDiscovery
+  tests({
-  },
+    setup () {
-  teardown () {
+      return YourDiscovery
-    // Clean up any resources created by setup()
+    },
-  }
+    teardown () {
-}
+      // Clean up any resources created by setup()
-
+    }
-// use all of the test suits
+  })
-test(common)
+})
 ```
 
 ## API