Update facade docblocks

Author: taylorotwell

src/Illuminate/Support/Facades/DB.php

@@ -101,10 +101,10 @@
  * @method static \Illuminate\Database\Connection setReadWriteType(string|null $readWriteType)
  * @method static string getTablePrefix()
  * @method static \Illuminate\Database\Connection setTablePrefix(string $prefix)
- * @method static \Illuminate\Database\Grammar withTablePrefix(\Illuminate\Database\Grammar $grammar)
+ * @method static void withTablePrefix(\Illuminate\Database\Grammar $grammar)
  * @method static string getServerVersion()
  * @method static void resolverFor(string $driver, \Closure $callback)
- * @method static mixed getResolver(string $driver)
+ * @method static \Closure|null getResolver(string $driver)
  * @method static mixed transaction(\Closure $callback, int $attempts = 1)
  * @method static void beginTransaction()
  * @method static void commit()