Update MessageInterface.php

Moved in docs in php-fig#86

Author: WinterSilence

src/MessageInterface.php

@@ -46,18 +46,6 @@ public function withProtocolVersion($version);
      * The keys represent the header name as it will be sent over the wire, and
      * each value is an array of strings associated with the header.
      *
-     *     // Represent the headers as a string
-     *     foreach ($message->getHeaders() as $name => $values) {
-     *         echo $name . ": " . implode(", ", $values);
-     *     }
-     *
-     *     // Emit headers iteratively:
-     *     foreach ($message->getHeaders() as $name => $values) {
-     *         foreach ($values as $value) {
-     *             header(sprintf('%s: %s', $name, $value), false);
-     *         }
-     *     }
-     *
      * While header names are not case-sensitive, getHeaders() will preserve the
      * exact case in which headers were originally specified.
      *