feat(checkbox): add helper and error text styles

Author: brandyscarney

core/src/components/checkbox/checkbox.ionic.scss

@@ -108,6 +108,21 @@ input {
   fill: var(--checkmark-color);
 }
 
+// Checkbox Hint Text
+// ----------------------------------------------------------------
+
+.checkbox-bottom {
+  @include globals.typography(globals.$ion-body-md-regular);
+}
+
+.checkbox-bottom .error-text {
+  color: globals.$ion-semantics-danger-800;
+}
+
+.checkbox-bottom .helper-text {
+  color: globals.$ion-primitives-neutral-800;
+}
+
 // Label Placement - Start
 // ----------------------------------------------------------------