style(): unify docs and spacing (#1448)

* typo(barcode-scanner): fixe circle lint error

* typo(docs):  Unified the documentations

In some plugins the typescript markup was missing.
I also unified the console.log string from console.log("hello") to console.log('Hello') so any plugin page look the same.

src/@ionic-native/plugins/serial/index.ts

@@ -20,8 +20,7 @@ export interface SerialOpenOptions {
  * This plugin provides functions for working with Serial connections
  *
  * @usage
- *
- * ```
+ * ```typescript
  * import { Serial } from '@ionic-native/serial';
  *
  * constructor(private serial: Serial) { }