Add support of watermark in init method

README.md

@@ -26,7 +26,8 @@ composer require muvon/bitclout-creator-coin
     ```php
     use Muvon\Bitclout\CreatorCoin;
     $Coin = CreatorCoin::create(0); // pass reward basis points
-    $Coin->init(1000, 1000); // locked and supply in nanos
+    // Watermark is optional
+    $Coin->init(1000, 1000, 0); // locked, supply and watermark in nanos
     ```
 
 ### Emulate buys

src/CreatorCoin.php

@@ -48,15 +48,17 @@ public static function create(int $reward): static {
    *   Locked amount in nanos
    * @param int $supply
    *   Total supply in $creator coins in nanos
+   * @param int $watermark
+   *   Optional watermark in case we use same strategy
    * @return static
    */
-  public function init(int $locked, int $supply): static {
+  public function init(int $locked, int $supply, int $watermark = 0): static {
     if ($this->supply > 0) {
       throw new Exception('Creator coin was inited already');
     }
     $this->locked = $locked;
     $this->supply = $supply;
-    $this->watermark = $supply;
+    $this->watermark = max($supply, $watermark);
     $this->recalculateRate();
     return $this;
   }