Remove Duplicate Word in Comment (Loop Interface)

Remove a duplicate word ("the") from the comment for `LoopInterface::addPeriodicTimer`.

Author: Ben Roberts

README.md

@@ -590,9 +590,9 @@ The return value of the timer callback function will be ignored and has
 no effect, so for performance reasons you're recommended to not return
 any excessive data structures.
 
-Unlike [`addTimer()`](#addtimer), this method will ensure the the
-callback will be invoked infinitely after the given interval or until you
-invoke [`cancelTimer`](#canceltimer).
+Unlike [`addTimer()`](#addtimer), this method will ensure the callback 
+will be invoked infinitely after the given interval or until you invoke 
+[`cancelTimer`](#canceltimer).
 
 ```php
 $timer = $loop->addPeriodicTimer(0.1, function () {

src/LoopInterface.php

@@ -213,9 +213,9 @@ public function addTimer($interval, $callback);
      * no effect, so for performance reasons you're recommended to not return
      * any excessive data structures.
      *
-     * Unlike [`addTimer()`](#addtimer), this method will ensure the the
-     * callback will be invoked infinitely after the given interval or until you
-     * invoke [`cancelTimer`](#canceltimer).
+     * Unlike [`addTimer()`](#addtimer), this method will ensure the callback 
+     * will be invoked infinitely after the given interval or until you invoke
+     * [`cancelTimer`](#canceltimer).
      *
      * ```php
      * $timer = $loop->addPeriodicTimer(0.1, function () {