message: docs(operators): fix marble-diagram image src
  * docs(operators): fix marble-diagram image src
  Updating to proper marble diagram image src property for buffer operator
diff: @@ -12,7 +12,7 @@ import { OperatorFunction } from '../types';
  * <span class="informal">Collects values from the past as an array, and emits
  * that array only when another Observable emits.</span>
  *
  - * ![](content/img/buffer.png)
  + * ![](buffer.png)
  *
  * Buffers the incoming Observable values until the given `closingNotifier`
  * Observable emits a value, at which point it emits the buffer on the output
  