Add page to puny melting about sand cast creation in the part builder

(cherry picked from commit cfe73b9)

src/main/resources/assets/tconstruct/book/puny_smelting/en_us/casting/sandcast2.json

@@ -4,5 +4,10 @@
     "file": "tconstruct:book/images/sand_pick.png",
     "width": 119,
     "height": 100
-  }
+  },
+  "text": [
+    {
+      "text": "Sand casts can be created by pressing a tool part into a casting table filled with sand."
+    }
+  ]
 }

src/main/resources/assets/tconstruct/book/puny_smelting/en_us/casting/sandcast3.json

@@ -0,0 +1,13 @@
+{
+  "title": "Sand Casts",
+  "image": {
+    "file": "tconstruct:book/images/sandcast_partbuilder.png",
+    "width": 172,
+    "height": 74
+  },
+  "text": [
+    {
+      "text": "Sand casts can also be created in the part builder by placing sand or a blank sand cast in the pattern slot. This is required to create armor plating casts."
+    }
+  ]
+}

src/main/resources/assets/tconstruct/book/puny_smelting/sections/casting.json

@@ -22,6 +22,11 @@
     "type": "mantle:crafting",
     "data": "casting/sandcast_craft.json"
   },
+  {
+    "name": "sand_cast3",
+    "type": "mantle:image_text",
+    "data": "casting/sandcast3.json"
+  },
   {
     "name": "gold_cast",
     "type": "mantle:image_text",