Create valid-longitude.md

Author: milwad-dev

docs/1.x/valid-longitude.md

@@ -0,0 +1,11 @@
+## ValidLongitude
+
+If you want to validate the longitude, you can use the `ValidLongitude` rule:
+
+```php
+use Milwad\LaravelValidate\Rules\ValidLongitude;
+
+return [
+   'longitude' => ['required', new ValidLongitude], // longitude => 51.377225156511855
+];
+```