title: How to have Or between vee-validate3 rules?
body: <p>i have an input that its value can be username or email
  consider this:</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;ValidationProvider name="email" rules="username || email"    v-slot="{ errors, valid }"&gt;
    &lt;v-text-field
      v-model="something"
      :error-messages="errors"
      :success="valid"
      label="E-mail or userName"
      required
    &gt;&lt;/v-text-field&gt;
  &lt;/ValidationProvider&gt;</code></pre>
  </div>
  </div>
  </p>
  <blockquote>
  <p>I need Or between rules. if one of them match pass the input.</p>
  </blockquote>
  <p><strong>rules=&quot;username or email&quot;</strong>
  how to achieve this in vee-validate3?</p>