In your resources/lang/en/password.php change the sent value:
'password' => 'Passwords must be at least six characters and match the confirmation.',
'reset' => 'Your password has been reset!',
'sent' => 'We have e-mailed your password reset link!', // this one
'token' => 'This password reset token is invalid.',
'user' => "We can't find a user with that e-mail address.",
@ZXTANZXZX - If you don't want to change the translation value, and you want to change the html instead, then you can change it on the view resources/views/auth/passwords/email.blade.php:
@if (session('status'))
<div class="alert alert-success" role="alert">
{{ session('status') }} <- change it to your preferred text
</div>
@endif