fix(docs): Fix esdoc for Observable.merge spread argument

src/operator/merge.ts

@@ -123,8 +123,7 @@ export function mergeStatic<T, R>(...observables: (ObservableInput<any> | Schedu
  * @see {@link mergeMapTo}
  * @see {@link mergeScan}
  *
- * @param {Observable} input1 An input Observable to merge with others.
- * @param {Observable} input2 An input Observable to merge with others.
+ * @param {...Observable} observables Input Observables to merge together.
  * @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input
  * Observables being subscribed to concurrently.
  * @param {Scheduler} [scheduler=null] The Scheduler to use for managing