Add GameShipKit browser tools (sprites, rigging, maps, textures) (#499)

Co-authored-by: johnisking <support@gameshipkit.com>

README.md

@@ -123,6 +123,7 @@ _Great graphics placeholders and tools to turn that squared game into a picasso
 #### Texture Tools
 
 - :moneybag: [FilterForge](https://www.filterforge.com/) - A plugin for Adobe Photoshop that allows you to build your own filters.
+- :money_with_wings: [GameShipKit Sprite Normal Map](https://gameshipkit.com/tools/sprite-normal-map/) - Generate normal maps from 2D sprites for lit 2D scenes.
 - :free: [Live Normal](https://tenebrislab.github.io/livenormal/) - An Android and iOS app for generating seamless materials on the go. You take a photo, and Live Normal creates a tile-able texture and generates texture maps ready for a PBR engine of your choice.
 - :tada: [MeshCoat](https://stuyk.github.io/meshcoat) - Fast, offline desktop texture painter: load a 3D model and paint PBR materials directly onto the mesh, then export texture maps. [Source](https://github.com/stuyk/meshcoat)
 - :free: [Nebula Forge](https://nebulakit.itch.io/nebula-forge) - Browser-based procedural nebula background generator with adjustable controls and PNG export. Runs locally without signup.
@@ -133,10 +134,13 @@ _Great graphics placeholders and tools to turn that squared game into a picasso
 #### Character Generators
 
 - :free: [Charas](http://charas-project.net/index.php) - Charas is a charset generator for RPG Maker.
+- :money_with_wings: [GameShipKit 2D Character Rigging](https://gameshipkit.com/tools/character-rigging/) - Rig a 2D character in the browser and export idle, walk and attack animations as sprite sheets.
 
 #### Tile/Level Editors
 
 - :moneybag: [AutoTileGen](https://pixelatto.com) - AutoTileGen is an automatic tileset generator for 2D game terrains.
+- :money_with_wings: [GameShipKit Autotile Generator](https://gameshipkit.com/tools/autotile-generator/) - Make blob and RPG Maker style autotiles from two textures, with Godot 4 and Tiled tilesets.
+- :money_with_wings: [GameShipKit Map Generator](https://gameshipkit.com/tools/map-generator/) - Seeded dungeon, cave and island maps, exported as PNG, Tiled JSON and CSV.
 - :tada: [LDtk](https://deepnight.net/tools/ldtk-2d-level-editor/) - LDtk is an open-source 2D level editor for indie devs, with a strong focus on user-friendliness.
 - :money_with_wings: [MapperMate](https://mappermate.com/) - A cloud based tile map editor used to create 2D levels directly in the browser.
 - :tada: [Material Maker](https://github.com/RodZill4/material-maker) - procedural texture creator made in Godot